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问题 单项选择题

以下关于华为路由器软件远端环回操作的指令正确的是（）

A.loopback-detect local

B.loopback-detect remote

C.loopbacklocal

D.loopbackremote

答案

参考答案：D

计算题

火车车厢之间由车钩连接，火车起动前车钩间都有间隙。不妨将火车的起动简化成如图所示的情景：在光滑水平面上有19个静止的质量均为m的木箱，自右向左编号依次为0、1、2、3、……18，相邻木箱之间由完全非弹性的钩子连接，当钩子前后两部分相碰时，与钩子相连的两木箱速度立即变为相等。所有木箱均静止时，每一个车钩前后两部分间的距离都为L。

（1）若只给第0号木箱一个水平向右的初速度υ0，求第18号木箱刚运动时速度的大小；

（2）若从某时刻开始，持续对第0号木箱施加向右的水平恒力F，使木箱从静止开始运动，求

（i）第1号木箱刚运动时速度的大小；

（ii）从施加恒力F到第18号木箱开始运动经历的时间。

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单项选择题

After observing the Earth’s weather patterns and the 11-year sunspot cycle of the Sun for 36 years, scientists have found that high levels of sunspot activity precede shifts in wind patterns that affect the Earth’s weather. One can conclude that meteorologists will be able to improve their weather forecasts based on this information.
Which of the following, if true, most seriously weakens the argument above

A．Weather forecasts are more detailed today than they were 36 years ago.

B．Scientists can establish that sunspot activity directly affects the Earth’s weather.

C．Evidence other than sunspot activity has previously enabled meteorologists to forecast the weather conditions that are predictable on the basis of sunspot activity.

D．Scientists have not determined why the sunspot activity on the Sun follows an 11-year cycle.

E．(E) It has been established that predictable wind patterns yield predictable weather patterns.
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