先通读下面的短文，掌握其大意，然后从A、B、C、D四个选项中选择可以填入空白处的最佳答案。

    I have a good friend.Her1 is Helen.She is a2girl and she is good to us.But she often3her pens and books.Luckily(幸运地)，her4are good to her, too.They help her a lot.She feels very happy about this.This morning5the class，Helen can't find her pencil box.She is not happy because (因为)her6are in it，and she can't write without(没有)them. After class，we look for the pencil box and find7pencil boxes in the school library.They have different(不同的)8.One is yellow and one is green，Helen says the yellow one is9.We are very happy and Helen10us a lot.