Cette phrase est correcte: j'irais au musée si j'avais le temps.
select one:
true
false

cette phrase est correcte: nous allions au restaurant si nous serions riches.
select one:
true
false

cette phrase est correcte: si mes parents m'achèteraient une voiture, je serais heureux.
select one:
true
false

can you explain why along with the correct answer? and you!

1) True

2) False

3) False

Explanation:

All questions relate to the conditional verb tense.

You express that you would do something (conditional tense) if a certain condition was met (which is expressed with the imperfect tense).

1)  J'irais au musée si j'avais le temps.

(meaning of the phrase: "I would go to the museum if I had time")

The first verb (irais, is from verb 'aller' - to go)

The conjugation of aller in conditional present is: j'irais, tu irais, il/elle irait, nous irions, vous iriez, ils/elles iraient

The second verb (avais, is from "avoir" - to have), and it's also correctly conjugated in the imperfect since it's a condition.

2) Nous allions au restaurant si nous serions riches.

(meaning of the - correct - sentence: "We would go to the restaurant if we were rich")

Here, both verb tenses are wrong, they were inverted.

The first one, (allions, from "aller" - to go) is in imperfect, while it should be in conditional (irions, see above).

The second one (serions, is from "être" - to be), is in conditional, while it should be in imperfect since its a condition (étions)

So, the correct sentence would be "Nous irions au restaurant, si nous étions riches"

3) Si mes parents m'achèteraient une voiture, je serais heureux.

(meaning of the - correct - sentence: "If my parents would buy me a car, I would be happy")

Here, the first verb is incorrect.  "Achèteraient" is for verb "acheter" (to buy), in conditional form, while it expresses a condition.  Imperfect tense should  be used ('achetaient).

The second verb (serais, from "être" - to be) is correctly conjugated using the conditional.

The correct sentence would be "Si mes parents m'achetaient une voiture, je serais heureux"