What is the main idea of the following poem? fire and ice by robert frost some say the world will end in fire, some say in ice. from what i’ve tasted of desire i hold with those who favor fire. but if it had to perish twice, i think i know enough of hate to say that for destruction ice is also great and would suffice. fire and ice will take over the world. hate makes people coldhearted and deadly. hate and love are like fire and ice. either hatred or desire will destroy the world.

I think you could choose either fire or ice.
fire = desire.

Selfishly wanting what you should not have is selfish desire. It is ruinous to think only of yourself. That's fire in this case.

hate is also very destructive. (I personally think that hate is the most dangerous of all possible character traits.) Hatred has emotional roots that cannot be easily overcome and certainly is not controlled by a tender heart. Intellect can be very guilty of hatred. That is why it is termed ice. Hatred can be quite cold governed by intellect. 

It depends on the subject for me. some exams are easier than others so i usually go through it and answer questions i know based on my general knowledge, then double check after. going through the lesson can a lot  because the exams can be  very lesson-specific, but sometimes they are ridiculously long so a lot of people don't take the time. i did find that, when i went through the lessons, i was making 100's on my exams vs strictly using + the internet and  i make 90's.