题干
—Must I clean the room now?
—No, you . You can do it later.
A：needn't
B：can't
C：may not
答案(点此获取答案解析）
A
—Must I clean the room now?
—No, you . You can do it later.
A：needn't
B：can't
C：may not
Cu+Cu2+(未配平)。
气体产生；③溶液呈蓝色。