People need to breathe

people need to breathe. If they don't breathe, they ___ die. But how clean is the air people breathe? If they breathe ___ air, they will have breathing problems and become ill. Plants and animals need ___ air, too. A lot of the things in our lives create harmful gases and ___ the air dirty, like cars, motorbikes and factories. Dirty air is called "polluted air". Air pollution can also make our Earth warmer. 
Chọn đáp án đúng dưới đây và giải thích rõ vì sao lại chọn
(1): won't/are/must/will
(2) clean/fresh/dirty/cleaner
(3)clean/safe/dirty/polluted
(4) get/make/give/made
*** Trả lời cho hết,cho cả 4 phần, đừng trả lời mỗi 1 phần để nhận điểm thưởng, tôi sẽ mạnh tay báo cáo & đánh giá 1 sao