移行椎

与病情相符的临床表现是（）

A.相对缓脉常见于伤寒

B.双侧瞳孔散大见于脑疝

C.阵发性痉挛性咳嗽见于百日咳

D.少尿见于糖尿病

E.果酱样便见于阿米巴痢疾

如图所示，两根竖直固定的足够长的金属导轨ad和bc相距L=0.2m，另外两根水平金属杆MN和EF的质量均为m=10^-2kg，可沿导轨无摩擦地滑动，MN杆和EF杆的电阻均为0.2Ω（竖直金属导轨的电阻不计），EF杆放置在水平绝缘平台上，整个装置处于匀强磁场内，磁场方向垂直于导轨平面向里，磁感应强度B=1.0T，现让MN杆在恒定拉力作用下由静止开始向上加速运动，当MN杆加速到最大速度时，EF杆对绝缘平台的压力为零（g取10m/s²）

（1）定性说明在达到最大速度前MN杆的运动性质（不用说明理由）；

（2）达到最大速度时，拉力对MN杆做功的功率为多大？

指南针最早的形式叫什么？

Melissa and LoveLetter made use of the trust that exists between friends or colleagues. Imagine receiving an (16) from a friend who asks you to open it. This is what happens with Melissa and several other similar email (17) . Upon running, such worms usually proceed to send themselves out to email addresses from the victim’s address book, previous emails, web pages (18) .
As administrators seek to block dangerous email attachments through the recognition of well-known (19) , 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 (20) access to your network.

A．cracker

B．user

C．customer

D．client