变量。
参考答案：
指被研究的现象、事件或事物所反映出来的数量特征。
By the time you have completed the essential training, you ________ exposed to virtually every new feature of the course . [ ]
A. will have been
B. are
C. have been
D. will be
一般清洗用的化学溶液可采用（）与热水的混合溶液。
A、酸
B、碱
C、中性肥皂
D、酒精
