蚯蚓在土壤中活动，可以使土壤疏松，蚯蚓的排出物还能增加土壤肥力．这说明了（　　）

A．环境影响生物

B．生物影响环境

C．生物依赖环境

D．生物适应环境

— Have you been here before?

— Yes. This is the third time that I ______ to Shanghai.

A．come

B．came

C．have come

D．had come