_____ might be expected, the response to the question was very mixed.

How about the pollution in the countryside?—Luckily, it’s not as serious as _______ in the big cities.

How are you going to the Summer Palace? —We’re going there____ bike. [ ]

Do you have any plan for this summer vacation, Mary?— Sure, I’ d like to be a volunteer and help to ______ the Central Park.

Reading more helps ________ learn better.