3 . By the time the policemen arrived, the criminals _________ without leaving any clues(线索).

A．have escaped

B．were escaping

C．had escaped

D．escaped

4 . 下面每句一个错误，请在有错误的地方增加、删除或修改。
增加：在缺词处加一个漏字符号(∧)，并在其下面写出该加的词。
删除：把多余的词用斜线(\)划掉。
修改：在错的词下划一横线，并在该词下面写出修改后的词。
注意：每处错误及其修改均仅限一词。
1. Curiously, we looked around for other guests.
2. My deskmate is a girl whom we can get along easily.
3. That was the reason why he gave for his absence.
4. There was nothing else to do, we went home.
5. Quantities of food was spread out on the table.
6. Zheng He had over 300 ships, some of them were over 150 meters long.
7. I noticed the heavy objects went down more quickly than the smaller, lighter ones.
8. Eric the Red was forced to leave Iceland because he committed a murder, for which he got into trouble.
9. When he decided to set sail further west, there were 10000 Vikings live in Iceland.
10. Leif followed Biarni’s directions and sailed to where is believed to be the coast of present-day Canada.