1 表示原因 1）There are three reasons for this 2）The reasons for this are as follows 3）The reason for this is obvious 4）The reason for this is not far to seek 5）The reason for this is that 6）We have good reason to believe that例： There are three reasons for the changes that have taken place in our lifeFirstly，peoples living standard has been greatly improvedSecondly，most people are well paid， and they can afford what they need or likeLast but not least，more and
