Due to the extremely high speed of computer examinations, all the large-scale examinations now take standardized answer sheets as long as the test questions have exact answers to choose from, and candidates fill in the answer sheets with pencils of the selected answers , And then the cursor reader scans the answer sheet using the principle of light reflection. Since some problems need to be corrected after re-thinking and checking, or because of incorrect filling of the position, you need to erase and re-correct, so the modification will be inevitable. If the density of the pencil you use is too deep, such as 4B-6B, the black piece is painted out. When you wipe it off, you will find it difficult to wipe it completely. If you wipe it harder, you will probably answer the question. If the card is scratched, such a wrong mark is left on the answer sheet. When the photoelectric reader is scanning, it is possible to recognize this mark and mistakenly think it is your answer; if the density of the pencil you use Too light, for example, a pencil of class H, the handwriting will be very light, and it will also make it difficult to recognize the cursor reader. The cursor reader will probably ignore the lightly painted answer as if it is not selected. . As mentioned earlier, the concentration of 2B pencils is moderate, which is in line with the requirements of computer reading. Therefore, the photoelectric reader is uniformly set to recognize the light reflection of the 2B concentration. Any answer that reaches the standard 2B concentration can be used by the photoelectric reader. Accurately read and identify without any misjudgment. (ID-865471166485389) Portable Breast Pump Zhejiang Carebao Co., Ltd , https://www.carebao.com