垃圾车每天冲洗()次,摆放整齐,无强异味,停放于制定地点。
A.1
B.2
C.3
D.4
参考答案:A
In order to keep their trade _____, they would have to buy less goods in the United States. [ ]
A. balanced
B. balancing
C. to balance
D. being balanced
若要除去下列各物质中的杂质,写出所用试剂的化学式
(1)除去MgCl2中混有的少量MgCO3,可选用______溶液;
(2)除去FeCl2中混有的少量Cu2+,可选用______;
(3)除去Fe粉中混有的少量Al粉,可选用______ 溶液.