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【多选题】
用拉伸法测定弹性材料的杨氏模量中，下列说法正确的是（ ）A.
望远镜系统只需要调平，不需要与光杠杆等轴
B.
光 杠杆及镜尺系统一经调好，中途不得再任意变动，否则所测数据无效
C.
加、减砝码要细心，手轻轻托住砝码托盘，不得碰动仪器；而且需待钢丝伸缩稳定后方可读数。
D.
在测量钢丝伸长量过程中，不可中途停顿而改测其他物理量（如d、L、D等），否则若中途受到另外干扰，则钢丝的伸长（或缩短）值将发生变化，导致误差增大。
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【简答题】A．How to cover the cost of their legal fees. B．How to pr Nikki's sisters from using websites. C．How to pr the remaining photos on the Web from spreading. D．How to pr this from happening...
【单选题】The main purpose of the passage is to______.
A.
offer advice on how to prevent hip fractures
B.
emphasize the importance of health precautions
C.
discuss the seriousness of hip fractures
D.
identify the causes of hip fractures
【单选题】The purpose of this passage is ______.
A.
to give advice as to how to prevent hearing loss
B.
to define the effects of noise on human behavior
C.
to warn people of the danger of noise pollution
D.
to tell the difference between noise and sound
【单选题】What does the author tell us in this passage?
A.
How trees help prevent droughts and floods.
B.
The relationship between trees and man.
C.
How an empire fell to pieces in ancient times.
D.
A story of trees.
【多选题】How to prevent the virus?
A.
Don't eat wild animals.
B.
Wash your hands often.
C.
Go outside to do exercise.
D.
Spray with 75% alcohol.
【单选题】The author intends to ______ by this article.
A.
give advice on how to prevent obesity
B.
advertise for gyms
C.
suggest the harm of obesity
D.
recommend good solutions to heart disease
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