My parents showed__________ some old pictures that brought back sweet memories．

What’s wrong with my son, doctor? — ____________ serious, just a slight cold. He’d better drink some water.

It’s really ________ for us to know ________ boy.

I can __________ be a doctor. I don’t have enough patience at all.

It’s hard to believe____ the way out of the forest without the help of the local guide.