紧凑型荧光灯比白炽灯光效提高（）以上，寿命延长5~10倍，节电率达70%~80%。
A.2倍
B.4倍
C.10倍
参考答案：B
实现一个极降压运行有两种方式。（）
A.慢速降压
B.手动降压
C.快速降压
D.自动降压
An appropriate amount of temporary pressure can ______ a kind of motivation to do something well, but once it becomes constant or permanent, psychological problems are likely to _______. [ ]
A. act as; rise
B. play as; appear
C. work as; raise
D. serve as; arise
