开头:
It is often said that ... , 据说……/人们常说……
As the proverb says ... , 古人云……
It goes without saying that ... ,
It is clear/obvious that ... ,
Many people often ask ...
扩展:
It is true that ... ,
Everybody knows that ... ,
It can be easily proved that ... ,
No one can deny that ... 不可否认……
There is no denying that ... 不可否认……
The reason why ... is that ... ,
There is no doubt that ... ,
To take ... for an example (instance) ... ,
We know that ... ,
What is more serious is that ...
I do not believe that ... ,
Perhaps you'll ask why ...
That's why I feel that ...
结论:
in a word, in general, in short, above all, after all, generally speaking, finally, in conclusion, at last, in summary, as a result, above all, thus, eventually, on the whole(就整体而言),
From this point of view ...
On account of this we can find that ...