In my personal understanding, under normal circumstances, black gel pen can be scanned in the exam, whether it is a needle or a bullet. However, the scanning results may be affected by some factors, such as paper quality, ink concentration, scanner accuracy and so on. Usually, the examination institution will stipulate the use of a specific type of pen or ink to ensure the accuracy and reliability of scanning. If you are not sure what kind of pen you can use, please consult the examination institution or school for more specific guidance.

The diameter of the black pen used in the exam is 0.5 mm, which is the best. Generally, the formal exam is marked by computer, so writing with black pen will make the computer marking clearer.