Inner city mass transit is an important and complex subject.

This original approach enables a far more complete understanding of a very complex subject.

It is a very complex subject, that I do not think is well understood at all.

Readers should note the following is a brief description of a very complex subject.

These can be a useful introduction to an extremely complex subject.

He was known for writing articles that made complex subjects easy to understand.

Furthermore, they have carried out serious work on a highly complex subject.

Everyone knows that that is a very complex and sensitive subject.

It is the first time she has taken a play out of a single setting and attempted a more complex subject.

It is not my intent today to give a scientific lecture about a very complex subject.