1/ Without Mr.Brown's support we wouldn't have finished the work.
-> If
2/ He didn't take any medicine, so he feels worse now
-> If
3/ Keep silent or you will wake the baby up
-> If
4/ Mr.Brown lost his because he didn't bring the map along
-> If
5/ He found it extremely difficult to learn this subject
-> He had
6/ The coffee was too hot for me to drink
-> The coffee was so
7/ I couldn't go out because the weather was so bad
-> It was 
8/ Lan wrote four best seller before he was 20.
-> By the age
9/ I have not seen a more wonderful building anywhere
-> No where
10/ Without air, there would be no life on this planet
-> If