1)Therearethreereasonsforthis.
2)Thereasonsforthisareasfollows.
3)Thereasonforthisisobvious.
4)Thereasonforthisisnotfartoseek.
5)Thereasonforthisisthat...
6)Wehavegoodreasontobelievethat...
例如:
Therearethreereasonsforthechangesthathavetakenplaceinourlife.Firstly,people’slivingstandardhasbeengreatlyimproved.Secondly,mostpeoplearewellpaid,andtheycanaffordwhattheyneedorlike.Lastbutnotleast,moreandmorepeopleprefertoenjoymodernlife.
注:如考生写第一个句子没有把握,可将其改写成两个句子。如:Greatchangeshavetakenplaceinourlife.Therearethreereasonsforthis.这样写可以避免套用中的表达失误。