根据多普勒效应，下列说法中正确的有（　　）

A．多普勒效应只适用于声波

B．当波源和观察者同向运动时，观察者接收到的频率一定比波源发出的频率低

C．当波源和观察者相向运动时，观察者接收到的频率一定比波源发出的频率高

D．当波源和观察者反向运动时，观察者接收到的频率一定比波源发出的频率高

单词拼写。

根据下列句子所给汉语意思,写出空缺处各单词的正确形式。

1.  The idea ______(突然想到) to him in a dream.

2.  Mike didn't have much trouble ______(申请) for a job in the firm.

3.  Whoever breaks the law will not escape ______(惩罚).

4.  Scientists have made a major ______(突破) in the treatment of cancer.

5.  Alcohol is strictly ______(禁止) in that religious area.

6.  They discussed the matter calmly and ______(合情合理地).

7.  His performance did not live up to his father's ______(期望).  

8.  As far as I'm ______(意识到), nobody has done anything about it.

9.  She does a lot of ______(志愿的) work for the Red Cross.

10.  The crying child ran to its mother to be ______(安慰) .