This may explain why ____________/As a consequence____________
It goes without saying that____________
In fact, we can observe easily that in modern society,____________
As a proverb says, "Everything has two sides".
As a proverb says, "Where there is a will there is a way".
As is known to all, "No pains, no gains."
Let’s bring our discussion here to a more present and practical context. In today’s world,____________
I can say that if you have no experiences like these, your life is an inadequate one.
be of great benefit/damage to sb./sth.
The reason of ____________ is not so much ____________ as ____________
People differ greatly in their attitudes towards this problem. Some people hold the opinion that ____________ Others, [ however/on the contrary], maintain that ____________.
It is [urgent/necessary/convenient/desirable/advisable] for sb. to do sth.
have [trouble/a difficult time] [in doing sth./with sth.]
举例证：It can be given by a (well known/concrete) example that ____________. / In order to see this point clearly, let us to see an example:____________/To illustrate this, there is an example that is very persuasive:____________.
The main/first reason is that ____________.
First, we can observe easily that in modern society, ...
In the first place
To begin with, (a good roommate should ____________)
Besides, the further reason why I advocate AAA is that ____________.
[The second/another] reason for [my/people’s] propensity for A is that ____________
[The second/another] desirable quality for a good roommate is that ____________
The third reason, [not the last/however], goes this way: ____________
写完三条原因还可以再写：Maybe there are some other reasons( to show____________). But
it is generally believed that the reasons mentioned above are commonly acceptable.
Nevertheless I must admit that people can do well without AAA, but no one can ignore the additional convenience and satisfaction offered by AAA. Such experience will definitely be helpful in one’s later life.