The chemist reads his book or is this past tense?

I agree with JaclynWomack, but this sentence is confusing in English because they use "sa," meaning "his" book, but the reference subject is plural "chemists" or "Chimestele." This would require the owner of the book being referenced in an earlier sentence. The more natural standalone sentence would be "The chemists read John's book," or some similar male name.