It is said that visitors spend only half as much money in a day in Leeds as in London.
It is+形容词(e.g. important/necessary/obvious)+that
It is important that every student should be able to understand the rule of school.
Follow your doctor's advice, or your cough will get worse.
It is taken for granted that …
It has been taken for granted that women should take on all the housework.
When it comes to...
But when it comes to political systems, the Western model is only one of a few options.
As far as sb./sth. be concerned,...
As far as I am concerned, living in China is better than living abroad.
play an important part/role in
China plays an increasingly important role in today's world.
There is no denying that ...
There is no denying that courage is playing an important role in one's life.
pose a great threat to ...
Pollution poses a great threat to our existence.