Breakdown of Elles sont toutes composées d'une substance chimique.
être
to be
une
a / an (feminine)
elles
they (feminine)
de
of / from / any (in negative sentences) / about (concerning)
composer
to compose
chimique
chemical
toutes
all of them (f)
la substance
the substance
Questions & Answers about Elles sont toutes composées d'une substance chimique.
Why does this sentence use d' instead of par to introduce the chemical substance?
In the passive voice, the agent (the thing doing the action) is usually introduced by par. However, when a verb describes a state, condition, or physical makeup rather than a specific dynamic action, it uses de. The verb composer (to compose) describes a state of being made up of something, so we use de, which shortens to d' before the vowel in une.
Why does composées end with -ées?
Because this sentence is in the passive voice, which always requires the auxiliary verb être (here, sont). When using être, the past participle must agree in gender and number with the subject. Since Elles is feminine plural, you add an -e and an -s to composé.
Why is toutes placed between sont and composées, and why is it plural?
Here, toutes is a pronoun meaning 'all', and it must agree with the feminine plural subject Elles. In compound tenses or passive constructions, short pronouns like toutes or tous are placed right after the conjugated auxiliary verb (sont) and before the past participle (composées).
Why does the sentence say une substance chimique instead of just translating 'a chemical' as a single noun?
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