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问题 选择题

关于匀速圆周运动，下列说法中正确的有                （   ）

A．做匀速圆周运动的物体，在任何相等的时间内，通过的位移都相同

B．做匀速圆周运动的物体，在任何相等的时间内，通过的路程都相等

C．做匀速圆周运动的物体的加速度恒定

D．做匀速圆周运动的物体的加速度方向不一定指向圆心

答案

答案：B

题目分析：匀速圆周运动，指的是速度大小不变，方向时刻变化，且加速度时刻指向圆心的圆周运动，因此CD错，由于速度大小不变，所以单位时间内通过路程相等，因此A错B对。

点评：本题主要考查了匀速圆周运动的相关参数的理解，例如向心加速度等的理解

单项选择题

 Melissa and LoveLetter made use of the l:rust that exists between friends or colleagues.Imagine receiving an (1)from a friend who asks you to open it.This is what happens with Melissa and several other similar email (2).Upon running, such worms usually proceed to send themselves out to email addresses from the victim's address book, previous emails, web pages (3). As administrators seek to block dangerous email attachments through the recognition of well-known (4),virus writers use other extensions to circumvent such protection.Executable (.exe) files are renamed to .bat and .cmd plus a whole list of other extensions and will still run and successfully infect target users. Frequently, hackers try to penetrate networks by sending an attachment that looks like a flash movie, which, while displaying some cute animation, simultaneously runs commands in the background to steal your passwords and give the (5)access to your network.

空白（5）处应选择（）

A.cracker

B.user

C.customer

D.client
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配伍题 B型题

培育T细胞的器官是（）
有动脉周围淋巴鞘的器官是（）
滤过淋巴的器官是（）

A.胸腺

B.淋巴结

C.骨髓

D.脾

E.腭扁桃体
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