Scientists conclude that female cats tend to favor their right paws when _______ complex tasks.

The bike my father bought me last week ___ him 200 yuan.

单项选择（每题1分）We must think twice _____ we make the final decision

People who have regular physical exercise seldom catch a disease like H1N1 Flu, ______?

A talk on Chinese history ________ in our school next TuesdayAre you interested in it?— Sounds goodDo we need to buy tickets?