With a large amount of housework ______, he would rather ______ at home, helping his wife with it, than go golfing. 

A．remaining to be done, stay

B．remained to be done, stayed

C．remaining to do, to stay

D．remained to do, staying

胎儿与母体间进行物质交换的结构是（　　）

A．羊水

B．子宫

C．卵巢

D．胎盘