关于震颤的说法哪项错误A．震颤为心血管器质性病变的体征 B．震颤的发生系血液经狭窄的

It is reported, some needy students receive financial support from some kind people but never express our thanks. Personally, I think they are wrong. Though the helpers didn't expect any reward in return, it is necessary and good manner to say “thank you”. Besides, it is a basic social skill express ourselves in modern society. Maybe some of them do feel thankfully. It is only because they are afraid of looked down upon which they remain silent. But I just want to say that being poor for a moment doesn't means you will be poor forever.

兴奋性突触后电位产生时，突触后膜局部的变化为（）

A.极化

B.超极化

C.反极化

D.复极化

E.去极化

26. In the book, Newton is shown as a gifted scientist with very human weaknesses who stood at the point in history ______ magic ended and science began.

A．what

B．which

C．that

D．Where

在周期表主族元素中，X元素与Y、Z、W三元素相邻，X、Y的原子序数之和等于Z的原子序数；这四种元素原子的最外层电子数之和为20．下列判断正确的是（　　）

A．原子序数：Z＞Y＞X＞W

B．X、Y、Z、W形成的单质最多有6种

C．四种元素的气态氢化物中，Y的气态氢化物最稳定

D．X元素最高价氧化物对应水化物的化学式为H₃XO₄

可以使多个用户在各自的终端上同时使用同一台计算机的操作系统属于______操作系统。