Breakdown of Est-ce que tu as désinfecté l'aiguille ?
tu
you (informal singular)
avoir
to have
est-ce que
is it that / do / does (question marker)
l'aiguille
the needle (f)
Questions & Answers about Est-ce que tu as désinfecté l'aiguille ?
Since l'aiguille is feminine, why doesn't désinfecté end with an -e?
In the passé composé with the helper verb avoir, the past participle only agrees with the direct object if that object comes before the verb. Here, l'aiguille comes after as désinfecté, so the participle stays in its default masculine singular form.
How do you pronounce the -gui- part of l'aiguille?
Unlike words like guitare or guide where the u is silent, the u in aiguille is pronounced. It sounds like "gwee" followed by a "y" sound for the -ille. The whole word is roughly pronounced "eh-gweey".
If I wanted to give advice and say 'It is better to disinfect the needle', how would I use il vaut mieux?
You would say Il vaut mieux désinfecter l'aiguille. Remember that il vaut mieux (it is better) is an impersonal expression that is followed directly by an infinitive verb. You don't need to add a preposition like de before désinfecter.
Could I ask this question using inversion instead of est-ce que?
Yes! To sound a bit more formal, you could invert the helper verb and the subject pronoun: As-tu désinfecté l'aiguille ? In everyday spoken French, however, using est-ce que or simply keeping the statement order and raising your voice at the end (Tu as désinfecté l'aiguille ?) is much more common.