电气化铁路的输电线常用图所示的方式悬挂在钢缆上.钢缆的A端固定在电杆上,B端连接

题型:选择题

问题:

电气化铁路的输电线常用图所示的方式悬挂在钢缆上.钢缆的A端固定在电杆上,B端连接在滑轮组上.滑轮组由a、b、c三个滑轮构成,配重P由多个混凝土圆盘悬挂在一起组成,配重的总重为G,若不计摩擦和滑轮的重量,则以下说法中正确的是(  )

A.a为动滑轮,B端钢缆受到滑轮组的拉力大小约为3G

B.a为动滑轮,B端钢缆受到滑轮组的拉力大小约为G

C.a、c为动滑轮,B端钢缆受到滑轮组的拉力大小约为3G

D.a、c为动滑轮,B端钢缆受到滑轮组的拉力大小约为G

考点:定滑轮及其工作特点动滑轮及其工作特点
题型:选择题

根据短文内容,选择正确的答案。

       This is Mr. Black's family. Mr. and Mrs. Black have two sons and a daughter. They are from England.

They have a big house. There's a kitchen, a sitting-room, two bathrooms and three bedrooms in it. They have

a small but nice garden in front of the house. There are many beautiful flowers and some green grass in the

garden. And there are three tall trees near their house. They have two cars. They often go to the parks in their

cars at the weekends.

1. The Blacks are from _____________.[ ]

A. China

B. English

C. America

D. England

2. How many people are there in the family?[ ]

A. 3

B. 5

C. 6

D. 7

3. Their garden is ____________.[ ]

A. big

B. small

C. small but nice

D. big and nice

4. How many rooms are there in the house?[ ]

A. 4

B. 6

C. 7

D. 8

5. What's in the garden?[ ]

A. Many flowers and some grass.

B. Three trees and some grass.

C. Some trees and flowers.

D. Three trees and some flowers.

题型:选择题

属于不可修复元件的是()。

A.发电机

B.变压器

C.电容器

D.断路器

题型:选择题

我们学习化学以后就要用化学的观点看待我们身边的各种物质.请你写出一种你最熟悉的物质______,该物质的化学式______,从物质分类的角度它属于______(填“单质”、“氧化物”、“酸”、“碱”或“盐”).我们还知道物质的用途主要由物质的性质决定的,请你写出该物质的一种用途:______,决定这种用途的性质是______.

题型:选择题

医疗机构处方管理正确的是()

A.急诊处方3日有效,每张处方不超过3日量

B.门诊处方3日有效,普通药每张处方不超过7日量

C.麻醉药品注射剂每张处方不超过3日量

D.二类精神药品每张处方不超过3日量

E.普通药品处方保存1年,特殊管理的药品处方保存3年

题型:选择题

团支部多长时间进行一次团课()

A、每月

B、每季度

C、每半年

D、每年

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