皮皮学，免费搜题
登录
搜题
【单选题】
听力原文：W: You have a telephone call, Mr. Smith. M: Who is it? W: He didn't say. M: Tell him I'm not in the office. Say I'll be back by four o'clock. W: All right. Hello, sir... ? M: Yes? W: I'm afraid he's just stepped out of the office. May I ask who's calling? M: Yes, this is Edgar Davis from Boston. W: Oh, yes, Mr. Davis. I am afraid he won't be back until four o'clock. Could you give me your number, please. M: Yes. What does Mr. Smith tell his secretary to say?A.
He'll phone the caller at four o'clock.
B.
He's out of his office.
C.
he'll be on the phone at once.
手机使用
分享
复制链接
新浪微博
分享QQ
微信扫一扫
反馈参考答案：
举一反三
【多选题】观看压力继电器原理动画,以下关于压力继电器的描述正确的有( )。
A.
当控制油压达到调定值时,推动控制活塞触动电气开关发生信号,控制电气元件实现液压传动系统的下一步动作。
B.
压力继电器是将压力信号转换成电信号的元件。
C.
压力继电器可以实现各执行部件顺序动作。
D.
压力继电器的调定压力为执行元件前一动作的最高压力。
E.
压力继电器由压力---位移转换装置和微动开关两部分组成。
参考解析：
知识点：
题目纠错 0
发布
