设备操作能手所必需的四种能力是什么？
参考答案：
发现异常能力、处理恢复能力、条件设定能力、维持管理能力。
Mr. Smith would have come to see you if it had been possible, but he _______ so busy.[ ]
A. was
B. had been
C. has been
D. were
The camera is _______expensive________ I can't afford it.
A．so, that
B．such, that
C．so, as to
D．enough, that
