He usually goes to school by bus,but he_

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问题选择题

He usually goes to school by bus, but he______ the bus yesterday. [ ]

A. didn't took

B. didn't take

C. not took

D. took

答案

单项选择题 B型题

消心痛治疗心绞痛的作用机制是（）。

A.通过抑制钙离子进入冠脉、周围血管壁平滑肌细胞内而扩张冠脉及周围血管

B.抑制血小板聚集

C.减慢心率、降低心肌收缩力、减少心肌耗氧量

D.扩张冠脉及外周血管，减轻心脏负担

E.改善心肌营养与代谢

单项选择题

我国船舶污染物排放标准化船舶生活污水在内河的排放最高允许值为：生化需氧量应≤（）mg/1，固体悬浮物≤（）mg/1，大肠杆菌数≤（）个/100ml。

A.50/150/250

B.50/100/250

C.100/100/200

D.50/50/250