题干
182. In the time of great trouble, the soldiers _______ their spirits by singing.
A：kept u
B：kept o
C：kept to
D：kept from
答案(点此获取答案解析）
A
A：kept u
B：kept o
C：kept to
D：kept from
表示的粒子：S；④两个铁离子：2Fe3+；⑤导电、导热性最好的金属：Ag；⑥+2价的镁元素：Mg2+．其中正确的有（ ）