The old scientist devoted most of his time __________ the space science.
–Look at the sign, sir. Would you mind ________ your cigarette?--Sorry, I will do it right away.
My mother often tells me _________ too fast because there are too many cars in the street.
_______ the girl is very young, she can speak English and French very well.
--What would we do first if we want to develop our village?--A lot of new roads _____, I think.
A minute’s success _________ the failure of years.