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问题 填空题

当系统中存在一个时间常数特别大的惯性环节1/（Ts+1）时，可近似地将它看成是积分环节（）（低频段大惯性环节）。

答案

参考答案：1/TS

单项选择题

已知标准砖的尺寸为240mm×115mm×33mm，灰缝为10mm，则砌1m半砖墙标准砖的用砖量为（）。

A.385块

B.527.1块

C.529.1块

D.1017.5块
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阅读理解
阅读理解。
     Su Hua is studying at Cambridge, UK. She has bought a bicycle and is worried about security
(安全). Her friend, Kate, found this article and sent it to her.

     Introduction
     A lot of crime is against bicycles. About 150,000 bicycles are stolen every year and most
are never found. You can prevent this happening by following a few careful steps.
     Basic Security
     Do not leave your bicycle in out-of-the-way places. Always lock your bicycle when you
leave. Secure it to lampposts or trees. Take off smaller parts and take them with you, for
example lights and saddles (车座).
     Locks
     Get a good lock. There are many different types in the shops. Buy one that has been tested
against attack. Ask for a recommendation from a bike shop.
     Marking
     Security marking your bike can act as a deterrent to a thief. It can also help the police find
your bicycle. It should be clearly written and include your postcode and your house or flat
number. This will provide a simple way to identify your bicycle.
     Registration
     There are a number of companies who will security mark your bicycle for you. They will
then put your registration number and personal details on their computer database. Then if
your bicycle is found it will be easy to contact you.
     Finally
     Keep a record of the bicycle yourself: its make, model and registration number. You can
even take a photograph of it. This will prove the bicycle belongs to you.

1. Which part of the text gives you information on how to lock up your bicycle when you leave it?
A. Locks.
B. Marking.
C. Registration.
D. Basic Security.
2. The underlined phrase "act as a deterrent to a thief" means ______.
A. help you recognize your bike
B. help the police find your bicycle
C. stop someone stealing your bicycle
D. stop you worrying about your bike
3. The article advises you to keep a record of your bicycle _______.

A. in the bike shop and your computer
B. in the police station and a security company
C. in a security company and your university
D. by yourself and in a security company

4. The main purpose of this article is _________.
A. to tell you what to do if your bicycle is stolenB. to suggest ways of keeping your bicycle safe
C. to give you advice on where to buy a good lock
D. to say why you shouldn't keep your bicycle in a quiet place
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