根据句意和首字母填入恰当的词 

1. We were completely in the d __    about his movements.    

2. Her answer is r_____.    

3. If you want to s  __    . money, you had better buy second-hand books.    

4. I w____ about the exam tomorrow because it's very difficult.  

5. I used to eat c____ all the time. It's bad for my teeth.

FIDIC合同条件规定，在颁发整个工程的移交证书时，由于工程变更而使合同价格的增加或减少合计超过有效合同价的( )时，应在合同价格中加上或减去一笔款额。

A．10%

B．15%

C．20%

D．25%