2, ab volume, the content on the volume surface is the same, the answer sheet is different, that is, the order is different. The horizontal order of volume A is 1, 2, 3, 4, and the vertical order of volume B is 1, 2, 3, 4, mainly to prevent people sitting in the front and back rows from copying each other.
Extended data:
The AB card of college entrance examination is used to prevent nearby students from cheating. If you use an A card, all the students around you are B cards. A card is generally vertical, and B card is generally horizontal. In order to prevent college entrance examination candidates from cheating, the examination paper is implemented as AB volume, commonly known as flower roll. Some will disrupt the order of multiple-choice questions, while others will change the arrangement of answer sheets. This is irregular.
The answer sheet is the same, but the test paper is different. Some are sent one after another, and some are sent randomly, so even if you can see the answer sheet of the person next to you, it is useless.