I don't know where I can post this letter .=I don't know _ _ _thi_英语解答

I don't know where I can post this letter .=I don't know _ _ _this letter .

人气：233 ℃　时间：2019-11-04 23:30:17

解答

填 how to send
I don't know how to send this letter
我不知道该怎样寄出这封信