-Do you know the boy________ is sitting next to Peter?-Yes. He is Peter's friend. They are celebrating his ________ birthday.
--Why do you like going to Kunming for a holiday? ---Because the weather there is _____too hot ______ too cold.
When H7N9 bird flu first appeared, people didn't know_______ doctors could cure it.
---Hurry up, _____you will miss the school bus. ---I know that, Mum. I’ll be ready in a minute.
Some people prefer yellow when they hope for__________.
The boy looks nice____white and the red sweater looks good _____the girl.