The best thing to do is to limit yourself to 1,000 calories a day to try to _____
The famous actor keeps fit by __for half an hour every morning.
The question at tomorrow’s meeting will be of importance.
When the food in the hotel where we are staying , what should we do?
Since you understand all this, is no need for me to explain.
—Is there any vaccine(疫苗) against H1N1 flu that can be used on humans? —No, but scientists are working to develop ________ .