根据句意和语境，用所给词的适当形成填空。

1．The teacher asked her students           (not forget)to sweep the floor．

2．Don’t look out of the window．Listen to the teacher           (care)in class.

3．Lucy’s sister lives on the           (twelve)floor．

4．For the        (begin)，it’s a little difficult to study English grammer．

5．The Greens          (enjoy)listening to the music，so they often go to the concert.