If I ______ about this computer program, a hage amountof time and energy would have been saved.

f the students have hardly ever beento the Grand Canyon, __

Who did you go to Huangshan Mountain with— No, I didn’t go with ________.

(江苏省南通市2009期末调研)－Mary, how did your Math test go?－I had thought I _________, but in fact I came in the top 10% in my class.

It is necessary that the government solutions for the problems of air pollution to create a clear environment.