Duolingo English Test Read and Complete: Word Families

You see an unfinished word inside a passage:

The new procedure led to a subs_______ reduction in processing time.

The opening letters suggest several shapes, but grammar and collocation narrow the decision. The blank follows an article and precedes a noun, so it needs an adjective. Substantial reduction is a natural combination, and the passage says the reduction was large. The completed word is substantial.

That is the central skill in Read and Complete: reconstruct unfinished words by combining the visible letters with evidence from the sentence and the passage.

Duolingo's current help page calls the task Read and Complete and gives the direction “Type the missing letters to complete the text below.” You complete unfinished words in a passage. The current page lists three minutes and advises reading the passage before focusing on individual words. Duolingo's current test-structure page lists the task three to six times. Its scoring page says responses are compared with correct responses and that partial credit is available; a blank and an incorrect response receive the same score for that blank.

This is not a prediction list. Duolingo's official guidance does not provide a finite test-word list to memorize; its structure page instead describes an extremely large question pool. The six families below are training material for reusable decisions. Continue at the Duolingo English Test vocabulary hub or see all six exam paths in Exam English.

Solve the passage before the fragment

Use five layers of evidence:

Whole-passage meaning: What is the paragraph explaining, comparing, or arguing?
Local grammar: Does the slot require a noun, verb, adjective, or adverb?
Visible letters: Which completion preserves every supplied letter in order?
Collocation: Which completed word forms a normal phrase with its neighbors?
Meaning boundary: Does the word make a stronger claim than the passage supports?

Do not begin by generating every English word with the same prefix. Read through once, identify the passage's direction, and then return to each fragment.

1. Prevalent: adjective or noun?

Prevalent means widespread or commonly occurring in a place, group, field, or period. Natural patterns include prevalent among + group, prevalent in + field, and increasingly prevalent.

Remote consultations are increasingly prev_____ in regional health services.

After increasingly, the sentence needs an adjective: prevalent. The noun is prevalence:

The prev______ of remote consultations varies by region.

The surrounding frame now requires a noun after the. Meaning also matters. Prevalent does not mean predominant. A practice can be common across many regions without being the single main practice.

Family map: prevail (verb), prevalent (adjective), prevalence (noun). Related forms are not interchangeable, and their stems do not remain perfectly identical.

2. Provisional: temporary status, not uncertainty alone

Provisional describes something arranged, accepted, or supplied for now but not yet final, often pending a named confirmation.

The committee released a prov_______ schedule while it waited for venue approval.

The noun schedule requires an adjective, and the pending approval explains why provisional fits. The adverb is provisionally:

The conference was prov_________ scheduled for May.

Do not reduce the word to “uncertain.” A tentative suggestion may be hesitant or not definite; a provisional schedule is operating as the schedule for now, subject to revision or confirmation. The context should show that interim status.

Family map: provision (noun or verb), provisional (adjective), provisionally (adverb). Shared letters do not make the meanings identical.

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3. Substantial: size or importance, not certainty

Use substantial for something large or important in its amount, degree, or extent.

The intervention resulted in a subs_______ fall in waiting times.

The article a and noun fall create an adjective slot. Substantial fall is a natural combination. The adverb is substantially:

Response rates were subs________ higher after the reminder.

That adverb modifies higher. Neither form says the result is certain, permanent, or caused by one factor. Those claims need separate evidence.

Family map: substance (noun), substantial (adjective), substantially (adverb). Be careful at the suffix boundary: the adjective is not formed by simply preserving the full spelling of substance.

4. Negligible: too small to matter in this context

Negligible describes an amount, difference, effect, cost, or risk so small that it is not worth considering for the present decision.

Under identical conditions, the difference between the two sensors was negl______.

After was, an adjective can complete the clause. Negligible fits only if the passage establishes that the difference does not matter here. It is more than a neutral synonym for small.

The adverb is negligibly. Keep this family separate from negligent, which means careless:

The calibration difference was negligible. The operator was negligent.

Both are real words, but passage meaning and noun selection separate them.

5. Conducive to: a fixed frame with a limited claim

Conducive to means tending to promote or provide favorable conditions for a result. It does not prove that the result occurred.

Quiet study areas can be cond_____ to sustained concentration.

The visible opening and fixed conducive to + noun or gerund pattern support the answer. Write conducive to learning, not conducive to learn and not conducive for learning.

Read the claim carefully. If a passage says quiet rooms helped create suitable conditions, conducive to fits. If it says the rooms directly and conclusively caused every improvement, the phrase alone does not express that full claim.

This expression also prevents a spelling trap: conductive concerns conducting heat or electricity in its central technical use; it is not the target adjective for favorable learning conditions.

6. Corroborate: additional evidence supports an existing claim

Corroborate is a transitive verb meaning support or strengthen an existing account, claim, or finding with additional evidence.

Satellite records corr_______ the measurements collected on the ground.

The plural subject takes the base-form present corroborate, and the direct object follows without a preposition. In the past:

Later records corr________ the original finding.

The answer is corroborated. The word does not automatically mean proved conclusively. It requires an existing claim and further supporting evidence. An isolated example may illustrate an idea without corroborating it.

Family map: corroborate (verb), corroborated (past or participle), corroborating (participle), corroboration (noun), corroborative (adjective).

Worked Read and Complete passage

The passage and fragments below are original practice, not recalled test content.

Flexible working arrangements have become increasingly prev_____ in large organizations. However, their effects are not uniform. A quiet home environment may be cond_____ to focused work, while limited space can create distractions. In one study, employees reported a subs_______ improvement in concentration on independent tasks, but a negl______ change during highly collaborative work. Because the first survey involved only one department, the researchers described their conclusion as prov_______. Data from a second department later helped corr_______ the original finding.

Answers and evidence

prevalent — increasingly needs an adjective; the arrangements have become widespread.
conducive — the fixed frame is conducive to focused work; it describes favorable conditions, not a guaranteed result.
substantial — the adjective modifies improvement and says the change was large or important.
negligible — the adjective modifies change and evaluates it as too small to matter in context.
provisional — the conclusion is being used for now but remains subject to confirmation because the first sample is narrow.
corroborate — after helped, the base verb fits; the second dataset supplies additional support for an existing finding.

Notice how the passage controls the answers. The first sentence establishes a topic, the contrast word however blocks an overgeneralization, and the final two sentences create an evidence sequence. Spelling alone would not establish all six choices.

A three-pass routine

Pass 1: read for direction

Ignore the fragments briefly. Identify the topic, contrasts, and evidence structure. Mark connectors such as however, because, while, and later.

Pass 2: classify each slot

Ask what grammar permits. An article before the fragment plus a noun after it often signals an adjective. To may be a preposition or part of an infinitive, so inspect the full phrase. A subject before the fragment and an object after it often signal a transitive verb.

Pass 3: rebuild and reread

Type the missing letters, then read the entire completed sentence. Check spelling, agreement, and claim strength. Finally, reread the passage because one answer can change your interpretation of a later fragment.

Common errors

Completing from the first letters only. A familiar beginning can belong to several family members.
Ignoring supplied letters. Your completion must preserve the visible form, not replace it with a synonym.
Choosing the right family but the wrong part of speech. Substance cannot fill an adjective slot for increase.
Treating collocation as proof. A familiar phrase must still match the passage meaning.
Overstating the evidence. Corroborate supports; it does not guarantee truth. Conducive to promotes conditions; it does not assert an outcome.
Calling every small number negligible. The passage must establish that the difference is unimportant for the present purpose.
Memorizing invented lists. Train real families in meaningful passages instead of trusting a claimed test-word inventory.

Controlled practice

Complete each word, then name the decisive clue.

The findings are prov_______ until the larger trial is complete.
The archive records corr_______ the witness's account.
The policy produced a subs_______ reduction in waiting time.
The price difference was negl______ relative to the maintenance cost.
Open discussion can be cond_____ to identifying hidden assumptions.
The practice is especially prev_____ among smaller firms.

Answers: 1. provisional; the later trial is a confirmation step. 2. corroborated; the records added support to an existing account, and past tense is required. 3. substantial; an adjective modifies reduction. 4. negligible; the comparison says it is too small to affect this decision. 5. conducive; the fixed pattern takes to + gerund. 6. prevalent; among + group marks widespread occurrence.

For each error, save the corrected word in a full pattern—provisional pending approval, corroborate a finding, a substantial reduction—rather than copying the isolated spelling repeatedly.

Sources

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