

1, The scientist are carrying out an important experiment.
2, People make cheese from milk
3, Did Wright brothers build the 1st plance in 1903?
4, WL Judison invented the zipper in 1983
5, People have used the ballpoint pens for many years
6, When I came, he was repairing the computer
7, Our factory doesn't produce this kind of paper
8, Van is going to repaint these rooms tomorrow
2, People make cheese from milk
3, Did Wright brothers build the 1st plance in 1903?
4, WL Judison invented the zipper in 1983
5, People have used the ballpoint pens for many years
6, When I came, he was repairing the computer
7, Our factory doesn't produce this kind of paper
8, Van is going to repaint these rooms tomorrow