Now people all over the world are _________the terrible H1N1 flu.

 I don’t know ________ such a difficult matter.

Driving on the road, drivers do ______ the traffic rules, which is responsible for themselvesas well as others.

 Every time ______ I go to school, I am usually riding my bike, _____ I take a bus.

Farmers often employ fertilizer or other special chemicals to _____the growth of crops, as is well-known.