味觉和嗅觉的相似之处是 ( )
A：感受的刺激都是化学物质
B：感受的刺激都是溶于水的物质
C：感受的刺激都是气体
D：感受器都位于皮肤内
— Driving on icy roads is very dangerous! The more ice there is, the _______ down the road you have to look．You should be more careful.
— OK, I will.
心脏瓣膜保证血液流动的方向是（ ）
下列与小肠的吸收功能无关的是（ ）
—____ does your father work?
—He works in a hospital.
