根据句意及汉语提示完成句子，每空一词。
1. Fish (吸入) oxygen through their gills (鳃).
2. Why do so many people try to climb Qomolangma (即使) it is dangerous?
3. You should never (放弃) trying to help others.
4. Will they change their mind if they are (面对) difficulties?
5. Humans can sometimes be stronger than the (大自然的力量).