People's Education Society has published two versions of senior high school mathematics textbooks, version A refers to the textbook written for version A (slightly simple) and version B refers to the textbook written for version B (difficult): the fractional points and coordinate translation of the four required vectors are deleted, the trigonometric identity transformation only needs to be deduced without memory, the trigonometric function is deleted with positive cotangent and cotangent, and other changes are not significant. If you want to buy it, look at whether the A version or the B version is written in the lower right corner of the cover of your textbook, and just buy the corresponding one.