---Where is your brother? ---He is in Beijing. He _____ back in three days.
Jet Li to Guangzhou for charity . He’ll come back in two days.
--- Doctor, ________ should I take this medicine? --- Twice a day.
The Math problem is too difficult , we really don’t know ________ to do it .
---What do you think of ______Bai Yansong?---He is _______ good host(主持人)that I like his program very much .
---Excuse me. Is the library open all day? --- . Only from 8 a.m. to 4 p.m.