1. every two…的意思是“每两个……”，后接复数名词。如：
He gets home leave every two years. 他每两年有一次探亲假。
You must take your medicine every two hours. 你得每两小时服药一次。
I have violin lessons every two weeks. 我每两个星期上一次小提琴课。
They are all expected to send in a written report every two months. 他们每两个月都得交一份书面报告。
2. every second…的意思是“每第二个……”，后接单数名词。如：
The nurse comes every second day. 护士每隔一天来一次。
We meet every second Tuesday. 我们隔周星期二见面一次。
从以上例句可以看出，every two和every second意思大致相同。另外，我们还可以说every other…，意思也差不多。如：
Write on every other line. 请隔行写。
We meet every other Tuesday. 我们隔周星期二见面一次。
I work every other day：Monday, Wednesday and Friday. 我隔天上班：每周一，三，五。
