Some biologists believe this is an ancient survival strategy, _______ a diet with 30 percent fewer calories than usual increased life span.
______ is obvious ______he has finished his work.
---Could I call you by the first name? ---Yes, you_______.
---Did you see the film last night? ---No, ________, but I was too busy.
Crazy English has over 20 million students all over China _____ the class through Internet.
---Do you work here?---No, I_______ the manager until the secretary comes back.A.will help B help C. helped D. am helping