冷却系统中出现的空气或燃气可用下列方法检测：将冷却系统中的溢油管连到1个盛水的水桶内，如果机器运行时桶内有（），则说明冷却水中含有（）。
参考答案：气泡；气体
—Is your father a teacher?
—Well, he _______. [ ]
A. used to
B. was used to
C. used to be
D. is used to be
Getting rid of bad habit is________forming a good one.[ ]
A. an effort much as
B. much an effort as
C. as an effort much as
D. as much an effort as
