He has done_______to improve his writing.
---What should I do, doctor? ---_____healthy, you should take more exercise.
--- Do you often watch Man and Nature on TV? --- Sometimes. It’s an interesting program, but I __________Sports News.
In the past few years there _________great changes in my hometown.
--- Don’t step on the grass next time, Mike. ---________.
They _______ in Nanjing since they came to China two years ago.