根据句意及首字母提示写出所缺单词。

1. He was so t _____ the night before his examination that he couldn't sleep.

2. Have all the guests been s _____ with food and drinks?

3. The new shoes are c _____ to wear.  I like them very much.

4. — What do you think of the fish?

    —It t _____ really delicious.

5. Some advertisements tell the t _____ and some don't.

缺乏工作文献时，（）的优势尤为明显。

A.问卷调查法

B.观察法

C.投射技术

D.工作日志法