重度急性有机磷杀虫药中毒时胆碱酯酶活性是（）
A.100%
B.90%～70%
C.70%～50%
D.50%～30%
E.30%以下
参考答案：E
—Why didn’t you ring me up?
—Sorry, I forgot your phone number. Otherwise, I _____ long before. [ ]
A. had rung you up
B. must run you up
C. would have rung you up
D. would ring you up
电弧焊件接头性能取决于焊缝金属半熔化区的金属性能。（）
