Learn Hardcore French: La nappe est blanche, mais elle sera vite couverte d’oignon et d’ail. - The tablecloth is white, but it will quickly be covered with onion and garlic.

Adjectives agree in gender and number with the noun after linking verbs like être. Blanc (masculine) becomes blanche (feminine) to match la nappe. This is an irregular pattern (c → che), like sec → sèche.

What tense is sera, and could I also say va être?

Sera is the simple future of être. You can also use the near future: elle va être couverte. Both are correct; sera is a bit more neutral/formal, while va être is very common in speech. With the adverb: elle sera vite couverte / elle va vite être couverte.

Why is vite placed between sera and couverte, and how does it differ from bientôt or rapidement?

Short adverbs like vite commonly go after the auxiliary and before the participle/adjective: elle sera vite couverte. Alternatives:

Elle sera très vite couverte (also common).
Elle sera couverte vite (possible but less idiomatic). Nuance:
vite = quickly (speed of becoming covered).
bientôt = soon (short time from now until it happens): elle sera bientôt couverte.
rapidement ≈ vite, a bit more formal.

What is couverte grammatically, and why does it end in -e?

It’s the past participle of couvrir, used in the passive voice: être + past participle. In the passive, the participle agrees with the subject, so feminine singular la nappe → couverte. Plural would be couvertes.

Why is it couverte de and not couverte par?

Use couvert(e) de + noun for the material/substance on the surface (e.g., couvert de neige, couvert de boue). Use par for the agent performing an action: la nappe a été couverte par les enfants (by the children).

Why are d’oignon and d’ail in the singular—shouldn’t they be plural?

Singular treats them as substances (mass nouns): couverte d’oignon/d’ail = covered with onion/garlic in general (e.g., chopped). Plural focuses on countable pieces: d’oignons (rings, slices). For garlic, the usual way to count is with cloves: des gousses d’ail. True plurals of garlic (ails, or archaic aulx) are mainly for varieties, not for quantity on a tablecloth.

Could I say de l’oignon or de l’ail here?

With adjectives like couvert/plein/garni/orné, French usually uses bare de for an unspecified substance: couvert de confiture/de chocolat. You can use a definite article if it’s a specific, previously identified substance: couvert de la boue du chantier. In your sentence, the bare de is the natural choice, so d’oignon/d’ail, not de l’….

Why the apostrophes in d’oignon and d’ail?

It’s elision: de becomes d’ before a vowel sound (and before silent h). Hence d’oignon, d’ail.

Is oignon the only spelling? How do you pronounce oignon and ail?

Both oignon and ognon are accepted (1990 reform), but oignon is more common. Pronunciation (approximate):

oignon ≈ “on-nyon” (two syllables; the final -on is nasal).
ail ≈ “eye”.
Whole tricky bit: d’oignon et d’ail ≈ “don-nyon eh dai”.

Is the comma before mais necessary?

A comma before coordinating mais is standard in French to mark the contrast: …, mais …. You’ll see it very often and it’s good practice.

Are these alternatives okay: Elle sera couverte vite, Elle va vite être couverte, Elle sera bientôt couverte?

Elle sera couverte vite: grammatically fine, but less idiomatic than sera vite couverte.
Elle va vite être couverte: very natural in speech.
Elle sera bientôt couverte: correct; nuance shifts from speed (vite) to imminence (bientôt).

Could I use recouverte instead of couverte?

Yes: elle sera vite recouverte d’oignon et d’ail. Recouvrir can suggest covering again or completely/over the top; agreement rules are the same as with couverte.

How would this change in the plural?

Adjective and participle agree in number: Les nappes sont blanches, mais elles seront vite couvertes d’oignon et d’ail.

Is vitement a word?

No. Use vite or rapidement.