$1. $ Because the world is getting warmer, polar bears are in danger of becoming extinct

$→$ Because dùng để chỉ nguyên nhân của sự việc, hành động

$2. $ I really enjoyed the concert athough the music was too loud

$→$ Although : Mặc dù

$→$ Although + S + V 

$3. $ While Paul was walking to the bus stop, he found somebody`s wallet on the ground

$→$ While + QKTD , QKĐ

$→$ Thì QKTD : S + was/were + Ving

$4. $ After Jackie is done with her chores, she will take out the trash

$→$ After + HTHT/HTĐ + TLĐ

$5. $ If you study for the test, you will do much better

$→$ Câu điều kiện loại 1 : If + S + V(s/es) , S + will/can/shall + V(nguyên mẫu)

$6. $ You should start early, otherwise, you won't get stuck in the traffic

$→$ Otherwise + Mệnh đề

$→$ otherwise : kẻo, nếu không thì

`@Chamian`