Lawrence Craven,a doctor from the USA,is the author of several published reports,one of     ________introduced the idea in 1953      aspirin could reduce the risk of heart attacks.

—Did you return Fred’s call? —I didn’t need to ____ I’ll see him tomorrow.

How can you expect to get anything____ you never give?

________ I’m __________ about the work. I’m not strong enough for it.

---Do you really want to go out? ---Yes, and I know it may rain           . I shall go out.