It ______ her half a year to learn how to drive. [ ]
A. cost
B. took
C. spent
D. paid
答案:B
泵并联工作时,扬程会()
毒鼠强中毒的主要发病机制是()
A.阻断中枢γ-氨基丁酸(GABA.受体或阻断氨基酸有关的离子通道
B.直接作用于副交感神经
C.增强肾上腺素能作用
D.抑制细胞色素氧化酶
E.抑制乌头酸酶,阻断三羧酸循环