1.表示原因1)Therearethreereasonsforthis.2)Thereasonsforthisareasfollows.3)Thereasonforthisisobvious.4)Thereasonforthisisnotfartoseek.5)Thereasonforthisisthat.6)Wehavegoodreasontobelievethat.例如:Therearethreereasonsforthechangesthathavetakenplaceinourlife.Firstly,peopleslivingstandardhasbeengreatlyimproved.Secondly,mostpeoplearewellpaid,andtheycanaffordwhattheyneedorlike.Lastbutnotleast,moreandmorepeopleprefertoenjoymodernlife.注:如写第一个句子没有把握,可将其改写成两个句子。如:Greatchangeshavetakenplac