— How did you catch the thief?

— Well, he ________ some goods into his bag when I came around a corner in the shop. So I caught him.

A．was putting

B．was put

C．have put

D．had put

向20℃的饱和澄清石灰水（甲溶液）中投入适量的氧化钙粉末，充分反应，下列说法错误的是（　　）

A．溶液温度未冷却到20℃时，溶液一定是饱和溶液

B．溶液温度未冷却到20℃时，溶质质量分数比甲溶液大

C．溶液温度恢复到20℃时，溶液质量比甲溶液小

D．溶液温度恢复到20℃时，溶液的溶质质量分数和甲溶液的相等