--I am very nervous about the coming exam.---Take it easy -J

take it easy,and make sure you are well prepared for it
cheer up 不如take it easy 妥当.cheer up ,可用于对方失败了活失落了,去鼓励他.
it doesnt matter.用于抱歉的回答.如：sorry ,i forgot to bring you the letter.------it doesn't matter.i have known about what it is about.