Of course, OG is the most important. It is better to do five books than to do five OGs.

Others have a complete understanding of Bai Yong's grammar, and Yang Peng's long and difficult sentences are also highly praised. Of course, a good foundation in Manhattan is ok, all in English, I have never tried it, hehe ~

I use Chen Xiangdong's logic, with Chinese translation, which is very efficient.

GMAT will also have PREP, that is, model testing software, and a cracked version. This is also an official topic, which is more authoritative.

I think the best ones are the 07 and 08 editions of GMAT Grammar Notes on CD, which are excellent, highly recommended, free of charge, downloaded and printed from the Internet. Both versions have been written, and the grammar is fine.

Math recommended baboon math notes.

Composition, I took Bobo's class, and Bobo's picture helped me a lot, but I didn't write it well in the end, hey ~

Good luck!