What is the correct way to use 'half as much ...... as' while comparing two things?

Question

Is the syntax correct in the following sentence?

You don't know half as much about New Zealand as you know about Australia.

I am trying to tell that your knowledge about New Zealand is less than half of your knowledge about Australia.

Can it be simplified as follows?

You don't know half as much about New Zealand as about Australia.

Answer 1

Yes, it can be simplified in the manner you put. In fact, I believe, that's how most natives use it.