测定外来化合物LD50 ,通常要求计算实验动物接触化合物多长时间内的总死亡数
A.2天B.4天C.7天D.14天E.30天
参考答案:D
根据下列句子及所给单词的首字母,在答题卷上按题号写出各单词的完全形式(每空限填一词)。
小题1:My grandfather likes to water the f______ in the garden on weekends.
小题2:The boy is too young. So don’t leave him a______ at home.
小题3:If I don’t help my mom do some h______ on weekends, my mother will be very angry with me.
小题4:Last night I didn’t go to bed u______ the TV program was over.
小题5:Last Sunday I w______ a letter to my father.
小题6:I need to look smart for my job i______.
小题7:He f______ his test last week. He should study hard.
小题8:He m______ his teacher in the street yesterday.
小题9:When the little girl saw the big tiger, she felt very s______.
小题10:Last week, I p______ 500 yuan for my new bike.
监测换热器的停机过程:();关闭监测换热器冷凝液出水阀门;关闭监测换热器循环水进水阀门;关闭监测换热器循环水出水阀门。