thank you for w_____ to me

thank you for writing ( letters, messages ) to me.

thank sb. for doing sth. 是一个固定格式，for 后面跟着的是名词，或动名词，如 writing, talking, listening 等动作。

writting
thank you for writting to me

writing

谢谢你的来信

What.自己心中有数