prep.+n./代词（宾格）/doing/being+adj.(adv)/宾语从句
如：for being late(adj.)
to do sth.(不定式)
to(介词) +n./代词（宾格）/doing sth.
sth. is important=sth. is of importance
sth. is valuable=sth. is of value
sth. is benefical=sth. is of benefit
介词相当于副词
知识点：
介词短语在句子中的功能：
1.在系动词后作表语
2.在名词后作后置定语
3.vt.+n.（宾语）+介词短语（宾补）
