降低氨合成塔入塔氨含量可以使合成率（）。
A.无法判断
B.上升
C.不变
D.下降
参考答案：B
-How was the professor’s lecture?
-Impressive. Thank you so much for giving me a lift during the rush hours. If not, I ________
the lecture today.[ ]
A. couldn’t attend
B. might not have attended
C. mustn’t have attended
D. can’t have attended
下述哪项不符合婴幼儿腹股沟疝（）
A.婴幼儿腹股沟疝为先天性疝
B.一般没有局部肌肉薄弱的改变
C.6个月以上的腹股沟疝有自愈机会
D.高位结扎术能达到满意疗效
E.嵌顿性腹股沟疝病儿应采取手术治疗
