Mg2+跨过质膜一般不会发生的跨膜形式是（）
A.扩散
B.易化扩散
C.主动转运
D.需要载体蛋白协助的转运
参考答案：A
Worried about the time _____, Mary had made a list of the sites she wanted to see in Beijing. [ ]
A. adequate
B. available
C. efficient
D. accessible
补偿器的安装要求有哪些？
