I want to be a writer when I.,类似的句子,when后面应该用什么时态?

各种都有，下面我选中学教材（新目标，可能还有小学和高中的句子，但主要是初中的）的一些句子给你看下：
When a friend gives you a present, open itand say “Thank you”.

Where were you when we cleaned the classroom? 我们打扫教室时，你在哪儿？
-Youshould turn off the shower when you’re washing your hair.
-It says you should take your ownbags when you go food shopping.
One difference is that sometimes it’s polite to make
noise when you’re eating, especially when you’re eating noodles.
In your country, what are you supposed to do when you meet someone for the first time?
In English, just like in Chinese, we change the way we speak when talking with different people.

when后用一般现在时.