用负压法检查罐顶板焊缝时，应封闭罐各出口，罐内负压不得小于（）mmH2O。
A、80
B、70
C、60
D、50
参考答案：D
She was so seized by panic from H7N9 that not a bird _______________.
A．did she dare to get close to
B．dared she to get close to
C．she dared get close to
D．she did dare to get close to
下列关于半夏对胃肠道的作用，错误的是（）
A.抑制胃液分泌
B.降低游离酸
C.抑制胃蛋白酶活性
D.胃黏膜损伤保护
E.增加胃黏膜PGE含量
