—David has made great progress recently.—_______, and __________.
I have heard a lot of good things about you I came back from abroad.
He wrote a letter ______ he explains what had happened in the accident.
Do not let any failures discourage you, for you can never tell ________ close you may be to victory.
Microblog is a platform ________ people can express their thoughts and communicate with each other by sending posts.
It was not until 1938 _________ the first colour TV programme was broadcast.