I have learned from my bitter experience　　　we don’t knowwe’ve got until it’s gone.

Elephants have their own way to tell the shape of an object and_________ it is rough or smooth.[ ]

What’s the matter with John He has beensitting there for hours.-A postcard from his fatheranattack of home-sickness in him.

The ______ he is, the _______he feels.

下列各句中，没有语病、句意明确的一项是（ ）