我一到那里就给你写信用英语怎么说

"I'll write you a letter as soon as I get there" 可以表达为 "我一到那里就给你写信"。

其中, "as soon as" 是一个短语, 意思是 "一......就......"，常用来表示将来的动作。

例如：

I'll call you as soon as I get home. (我一回家就给你打电话)
I'll send you the report as soon as it's ready. (我一准备好就给你发报告)

"write a letter" 意思是 "写信"。

例如：

I'm going to write a letter to my friend. (我要给我的朋友写信)
Have you written your letter yet? (你的信写好了吗？)