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问题 单项选择题

一列火车要通过一座长为60米的桥，测得火车头进入桥到火车尾离开桥需要20秒．又知这列火车通过一根电线杆需5秒，则火车长度为( )米．

A．( 15

B．( 20

C．( 25

D．( 30

E．( 35

答案

参考答案：B

解析： 设火车长为x米，车速为y米/秒，由题意知，火车20秒钟之内所走距离等于桥长加火车长，5秒钟所走距离等于火车长，于是有

解得x＝20，y＝4．故选(B)．

单项选择题

The nurse is delivering the client’s 10 AM medications. The client is away from his room for a diagnostic study. Which action is the most appropriate for the nurse to take

A. Leave the medications on the client’s bedside table.
B. Ask the client’s roommate to keep the medications for the client until he returns.
C. Lock the medications in the medicine preparation area until the client returns.
D. Have the client skip that dose of medication.
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问答题 简答题

简述犯罪动力发生的原理。
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