I/ They grow rice in tropical countries.
->Rice .........is grewn (by them) in tropical countries...............
2/ They have just introduced a new style of jeans in the USA
->A new style of jeans..........has been introduced (by them) in the USA.................
3/ They made jean cloth completely from cotton in the 18th century
->Jean cloths.........were made completely from cotton (by them) in the 18thth century...............
4/ They will produce five million bottles of champagne in France next year.
->Five million bottles of champagne........will be produced (by them) in France next year................
5/ They have built two department stores this year.
->Two department stores..........have been built (by them) this year..............
6/ You must do this exercise carefully
-> This exercise..........must be done carefully..............
7/ We can solve this problem.
->This problem.........can be solved ................
8/ People should stop experiments on animals.
->Experiments on animals ...........should be stopped by people...............
9/ We might find life on another planet.
->Life.........might be found by us on another planet.................