Ответ:
6. If people explore space , we`ll know much about stars and planets.
7. If these people take care of the environment, they don`t drop litter everywhere.
8. If Tom didn`t forget that it was Sunday, he wouldn`t get up early.
9. If I knew your telephone number , I would call you .
10. If Alex trained hard last month, he would win the game.
11.If forests weren`t cut down in the past,many species of animals and birds wouldn`t be destroyed.
12.If I knew about recycling ,I wouldn`t throw away a lot of rubbish.
Объяснение: