介词

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）