I wrote _____ my brother last Saturday, but I haven’t heard _____ him up to now. [ ]

There great changes in Nanjing in the past few years. –I agree. And some more lines of the underground will be in service this year.

Mr. Brown has worked in the factory ______15 years. [ ]

Don’tspend time beating ona wall, to change it into a door.

I am too busy to listen to her ____ talking. She has kept talking for about two hours.