Scientists around the world are working to a medicine for AIDS(艾滋病). ( cover)
My computer fan doesn't work.Where can I have it (repair)?
Why didn't you come to open the door for me?
I (wash)dishes in the kitchen and didn't hear the doorbell.
I didn't know (teach)children when I started to work in a primary school.
(luck),he got better before the important competition.
We hope that more (China)will win honour for our country.