“___"所需词从这几个中找：in,at,to,of,for,on1.Haveyougotused___sharingtheroomwithotherstudents?2.He'sbeenlookingforward___visitingParisforalongtime.3.Theyexplainedthattheyhadneverthought___doinganythingtooffend

　　“___"所需词从这几个中找：in,at,to,of,for,on

　　1.Haveyougotused___sharingtheroomwithotherstudents?

　　2.He'sbeenlookingforward___visitingParisforalongtime.

　　3.Theyexplainedthattheyhadneverthought___doinganythingtooffendus.

　　请写出空中所填介词,并且麻烦告诉我一下每句话用到了什么词组或者语法,所以才填这个介词.