亚历克斯正在写一封电子邮件，以便约翰知道他在做什么。

Alex is writing an email so that John will know what he is doing.

给国际学生杰克写一封电子邮件。

Write an email to Jack, an interational students.

给客户中心写一封电子邮件，要求一个及时的解决方案。

Write an email to the custom center to demand a prompt solution.

我正在写一封电子邮件给我的表哥.

I am an e - mail my cousin now.

例如，要是你在在嘈杂的咖啡馆里写一封电子邮件或在雨林里搜寻一只伪装的昆虫，能过滤掉外部的刺激就很有用。

It can be useful to filter out external stimuli if you are writing an email in a noisy coffee shop, for example, or are searching for a camouflaged insect in a rainforest.