Materials to prepare for the GEPT

Can anyone recommend some good materials I can use to prepare my students for the GEPT? I’ve been to the book shops and have a few books full of examples and stuff. All of the books I could find are in Chinese which is not a huge problem as the examples are in English, but I was just wondering whether there are any books in which even the instructions and other text is in English. Also, is the GEPT really the most useful qualification which they could be getting? Any opinions on the GEPT versus other tests?

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