I（主语）'ve arranged for（谓语） a car（宾语） to pick them up at the station（不定式短语做宾补）
有些动词在接sb to do sth 时,首先得有个介词（比如此句中的for)
结构：
动词 + 介词+ sb to do sth
拓展：
long for sb to do sth
wait for sb to do sth
depend on sb to do sth
rely on sb to do sth
call on sb to do sth