1)The Browns have bred endangered animals on their farm for 14 years.
-> Endangered animals have been bred on their farm by The Browns for 14 years.
2)I'm enjoying my new class but the study is really hard, so I won't be able to come back next weekend.
->Sarah told me that she was enjoying her new class but the study was really hard, so she wouldn't be able to come back the following weekend.
3)He isn't old enough to take that job.
->If he was old, he would take that job.
4)We can't clean up our polluted rivers and seas overnight.
->Our polluted rivers and seas can't be cleaned up overnight.
5)I advise you to put your money in the bank.
->If I were you, I would put my money in the bank.
6)Tom can't look up this word because he doesn't have a dictionary.
->If Tom had a dictionary, he could look up this word.7)Without plants, most water would run off as soon as it falls.
->If the plants isn't exist, most water would run off as soon as it falls.
8)Be careful or you will set your house on fire.
->If you are careful, you won't set your house on fire.
9)People speak English in international conferences.
->English is spoken in international conferences.
10)I haven't seen Kate since Christmas.
->Tom said he hadn't seen Kate since Christmas.