China began to open to the outside world in the late 1970s. _________, there have been great changes in the country.
I can’t swim. And she can’t, _______.
I was doing my homework _______ a dog came in.
—Marycan’thelp___thehouse.Why?—Becausesheisbusy____ahotelreservation.
It is about _______by bus from here to Harbin.
It’s impossible for us ____ there on foot in two hours.