断路器的操作机构，一般由哪几个部分组成？
参考答案：（1）能量转换机构；
（2）联动机构；
（3）保持机构；
（4）释放机构。
Principal White has been working in the school for about 20 years, ____all his energy to teaching and researching as well as the running of a healthy school.
A．devoted
B．devoting
C．to devote
D．devote
— _____?
— My telephone doesn't work. [ ]
A. Can I help you
B. Is that right
C. Who is it
D. What's the matter
