Difference between singular and plural pronunciation
I often can't discern the plural forms from the singular ones for words such as femme/femmes, homme/hommes, enfant/enfants. Any tips please?
In these cases, you have to pay attention to the pronunciation of the article (la,le,les). While the pairs femme/femmes, homme/hommes, and enfant/enfants, among others, share the same pronunciation, they are differentiated by their article. If you hear "lay" (or "layz" in the case of hommes), you know that the word is in plural form. Au contraire, if you hear "lah" or "luh," you know the word is in singular form.
In addition to enmar3's answer, sometimes it's clear by context. While the examples in the exercise can be difficult to discern, when you're actually talking with people, it will generally be pretty clear whether they're referring to a singular or plural noun, even if the pronunciation is the same.