单项选择题Smoking not only ______ the throat but can also cause cancer, loss of appetite and irregular heart beat.

单项选择题The small-business component of the local chambers of commerce ______ us is even more conspicuous.

单项选择题As a good photographer, you must develop an awareness of the world around you and the people who ______ it.

单项选择题Recent studies show that advertising usually ______ competition and therefore lower prices.

单项选择题Ministers are planning to fund an advertising campaign to ______ the risks of drunk-driving.