题目内容：

根据句子意思，用括号中所给单词的适当形式填空。

1.If you can go closer to the birds, you can _______ (easy) watch them.

2.He looks very sad because of his             (ill).

3.You can’t find many cranes here, because they live in much _____________(wet) place.

4.Every year many             (tour) come to visit the Great Wall.