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问题 单项选择题

一声纳装置向海水中发出超声波，其波的表达式为y=1.2×10-3cos（3.14×105t-220x）（SI）则下列结果中正确的是（）。

A.振幅A=1.2m

B.频率v=500Hz

C.波长λ=2.86m

D.波速u=1427m/s

答案

参考答案：D

阅读理解

阅读理解。

Dear Jim,

     Thanks for taking care of my house while I'm away. Please feed the cat and fish

every day.  The cat food is in the kitchen and the fish food is next to the cat food.  Also,

could you please check the cat's water bowl? The bowl is next to his food dish.

      Please water the plants twice a week. And could you take out the trash on Thursday?

They come for the trash then. Please check my mail box for me on Wednesday, too.

If you are hungry, help yourself.  There are drinks and foods in the fridge.

      Please don't forget to lock the door when you leave.

      Thanks again for your help.

                                                                                                              Yours,

                                                                                                               Mary

根据短文内容判断正（T）误（F）。

(    )1.  Jim is taking care of Mary's house.

(    )2.  The cat food is next to the fish food.

(    )3. Jim asks Mary to water the plants twice a week.

(    )4.  On Wednesday Jim needs to take out the trash.

(    )5.  Jim can't eat the food in the fridge.
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多项选择题

下列关于评价单元的技术对策措施的说法中正确的包括（）。

A.对评价单元存在的事故隐患，从技术上提出安全对策措施，可隔离、警告、连锁事故隐患，达到安全作业

B.利用安全距离防止人体触及危险或进入危险区，是减小或消除机械风险的一种方法

C.采用机械化和自动化技术使人的操作岗位远离危险或有害现场，能完全消除生产中的工伤事故

D.在比较危险的岗位或被迫按机器的节奏连续生产过程，使用机器人或机械手代替人来操作，使工作条件不断改善

E.尽可能以无毒或低毒的工艺和物料代替有毒、高毒的工艺和物料，是防毒的根本措施
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