it is a pity that every summer a few people drown at the beach. In some cases, these people were good
swimmers. So how did it happen? Riptide!
    Riptide is a strong underwater current. It moves quickly away from shore and out to sea. It appears
suddenly and pulls its victim under and far off shore. Therefore, people should make it a rule never to
swim too far out from the beach.
    If you find yourself in a riptide, don't panic. And by no means should you try to go against the tide
and swim back to shore. You'll tire yourself out and probably drown. Instead, swim parallel to the beach.
A riptide is very narrow. So just a few strokes in the right direction and you'll be out of danger.

be all ears 洗耳恭听
You are dead right. 对极了    dead adv.绝对地，完全地   deadly 致命的
be at sea    When we talked about business, I was at sea.   I am puzzled by what you said.
I make it a rule to get off early.
be in the habit of
By no means is he nice.  By no means did he tell the truth.
instead, ... = on the contrary
stroke n.(游泳的)划