Unit 4
　　1. I was halfway back to the cottage where my mother lived __________________________ (就在那时那男的追上了我).
　　2. __________________________(温度下降得这么迅速), we couldn't go on with the experiment.
　　3. In the southern part of the United States __________________________(有许多废弃的矿镇) built in the last century.
　　4. __________________________(火势最终被控制住了), but not before extensive damage had been caused.
　　5. By the time he arrives in Beijing, __________________________(我们都已经在这待了两天了).

　　Unit 4
　　1.when the man caught up with me
　　2. With the temperature falling so rapidly
　　3. are many abandoned mining towns
　　4. The fire was finally / at last brought under control
　　bring sth. Under control, get sth. under control ; sth. is under control
　　5. we will have stayed here for two days