题干
What are doing here? I ________ for you for ages!
A：have been looked
B：have been looking
C：looked
D：had been looking
答案(点此获取答案解析）
B
A：have been looked
B：have been looking
C：looked
D：had been looking
Cl ＋ 2MnCl 2＋ 5Cl 2↑ ＋ 8H2O反应中，氧化剂是