French language Q&A Forum

I am still confused about les and leur objects

In the lesson, there are two examples given:

1. Nous sommes gentils

2. On est gentils

In the second example, why is there “s” on the end of gentils? Should it not be gentil - since “on” is 3rd person singular?

I have gone to my notebook repeatedly, but the Kwik Kwiz says this:

You took this Kwiz 21 hours, 54 minutes ago.

This lesson is already in your notebook. Go to your notebook now to kwiz this topic as many times as you like.
How can I retake this quiz? I am struggling with this particular subject and really want to retake the kwiz.

I'm wondering if A2 exercises will also incorporate A1 lessons or if everything is self contained? I skipped a lot of A1 exercises because I was about 40% into A2 prior to starting and wanted to finish the level. 

Will I have to go back and complete A1 exercises in order to test myself of that criteria, or would it be included in A2 exercises? I just don't want to forget some random A1 lesson because I never see it again, especially as I start moving into higher levels.