托福作文开头套句：
When it comes to...， some think...
There is a public debate today that...
A is a common way of...， but is it a wise one?
Recently the problem has been broughtsintosfocus.
提出观点：
Now there is a growing awareness that...
It is time we explore the truth of...
Nowhere in history has the issue been more visible.
进一步提出观点：
...but that is the only part of the history.
Another equally important aspect is...
A is but one of the many effects. Another is...
Besides， other reasons are...
提出假想例子的方式：
Suppose that...
Just imagine what would be like if...
It is reasonable to expect...
It is not surprising that...
举普通例子：
For example(instance)，...
... such as A，B，C and so on (so forth)
A good case in point is...
A particular example for this is...
引用：
One of the greatest early writers said ...
"Knowledge is power"， such is the remark of ...
"...". That is how sb comment ( criticize/ praise...).
"...". How often we hear such words like there.
讲故事(先说故事主体)，this story is not rare
...， such dilemma we often meet in daily life
...， the story still has a realistic significance.
提出原因：
There are many reasons for...
Why ...， for one thing，...
The answer to this problem involves many factors.
Any discussion about this problem would inevitably involves ...
The first reason can be obliviously seen.
Most people would agree that...
Some people may neglect that in fact ...
Others suggest that...
Part of the explanation is ...
进行对比：
The advantages for A outweigh the disadvantages of...
Although A enjoys a distinct advantage ...
Indeed ， A carries much weight than B when sth is concerned.
A maybe ... ， but it suffers from the disadvantage that...
承上启下：
To understand the truth of...， it is also important to see...
A study of ... will make this point clear
让步：
Certainly， B has its own advantages， such as...
I do not deny that A has its own merits.
结尾：
From what has been discussed above， we may safely drawthe conclusion that...
In summary， it is wiser...
In short...