—How did your father smoking?—The doctor told him to do so,and he took the advice.
It is not easy to learn English well, but if you ____.You will succeed in the end.
--- _____ Tracy was in such a hurry ? ---I don’t know.She might have been running to catch the bus.
Stressful environment leads to unhealthy behaviors such as poor eating habits, which _____ increase the risk of heart disease.
—You don’t see the professor from Singapore quite often, do you? —No, we only meet ______.
Attempting to get home before dark, ___________