（）不是电控发动机谐波增压控制系统中的装置或部件。
A.真空控制阀
B.涡轮增压器
C.真空电磁阀
D.电子控制单元
参考答案：A
20.---------the English exam is difficult , isn’t it?
-------__Yes. Even Tom, ________to the top students, failed .
A．belonging
B．belonged
C．to belong
D．Belongs
It's a beautiful place. You should go and visit it if you have a ________. [ ]
A. money
B. hour
C. drink
D. chance
