IDIOMS

Olá pessoal,
Como poderia traduzir os seguintes idioms :

to go without saying:
It goes without saying that you should'nt drive quickly in bad weather.

to keep one's head:
When the boat starting sinking in heavy seas, the crew members kept their heads and led the passengers to the lifeboats.

to stand up:My old car stood up well over the years.

to get the better of:
Jim does not seem very good at tennis, but if you're not careful,he'll get the better of you.

to waste one's breath:Do not argue with Frank any longer.You are wasting your breath trying to get him to agree with you.

to step in :
When the children started fighting , a teacher had to step in and stop the fight.

Thank you folks