题干
—_________ you help me with my homework?
— Of course if I _________.
— Of course if I _________.
A：Could; could
B：Can't; can
C：Could; can
D：Can; could
答案(点此获取答案解析）
C
NH4++OH－，当其他条件不变时，改变下列条件，平衡向左移动，且NH4+浓度增大的是 ( )
