根据句意及所给提示，补全单词或用单词、固定短语、固定搭配的正确形式填空。

1. I w_____ if you can finish the work on time.

2. People in Korea are supposed ______ (bow) when they meet for the first time.

3. In the old days, the workers were made ______ (work) eleven hours a day.

4. I can't find ______ (适当的) words to describe her beauty.

5. I have ______ (借) his book for two weeks. I have to return it now.

下列造成短路的原因中属于人为原因的是（）。

A．鸟兽跨接在裸露的载流部分

B．运行人员带负荷拉刀闸

C．雷电造成避雷器动作

D．大风引起架空线电杆倒塌