题目内容：

根据句意或单词的首字母填写所给单词的正确形式。

1.The past few years have ________ (目睹)great changes throughout China.

2.Let's ________ (思考)on what we did.

3.She made a d_________ of $5,000 to the Children’s Hospital.

4.Since you have settled down in a new country, you have to make an a_________ to the new environment.

5.He was willing to participate in the _________ (自愿的) activity.