题目

The teacher expects us to do all the exercises, to study the spelling list and to get our paper ______ time.a. in b. on c. at d. by 答案：B将下列各组药品进行实验，能判别出铁比铜活泼的一组是 [　　] A.Fe、Cu、　　  　 B.Fe、Cu、 C.Fe、Cu、　　　D.Fe、Cu、