根据下图，下列叙述正确的是 A．此图表示神经冲动的传导过程 B．递质的释放过程是主动运输 C．2中不可能有抗体 D．递质与受体结合后，可引发3电位
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在等差数列{an}中，当a1=a5(r≠s)时，数列{an}必定是常数列，然而在等比数列{an}中，对某些正整数r,s(r≠s)，当ar=as时，{an}不是常数列的一个例子是_________.
补写出下列名篇名句中的空缺部分。 古代诗文中,有许多描写丝竹乐器演奏的名句,如李贺《李凭箜篌引》中的“ ，芙蓉泣露香兰笑”；白居易
You should put on the notices ________ all the people may see them. A. where B. in which C. at D. for them
设f(n)=+…+(n∈N*),那么f(n+1)-f(n)等于（ ） A. B.C. D.
完形填空 Hello! My name is Dave Brown. My 1 name is Dave. I play sports every day and I am very 2 . I eat a lot of fruit and 3 . For fruit, I like apples, oranges, pears and 4 . For vegetables,
The girl wanted to play in the park, but her mother told her ____. A. not to B. not to do C. to not do it D. to not
