Through their hard work, they _____ in climbing up to the top of the mountain..
I can’t swim. And she can’t, _______.
I was doing my homework _______ a dog came in.
—Mary can’t help ___the house. Why? —Because she is busy ____a hotel reservation.
It is about _______by bus from here to Harbin.
It’s impossible for us ____ there on foot in two hours.