Recently our class was very popular with a brush pen, and everyone used it to take notes, write homework and take exams. Why is that? It can be erased by the "eraser" behind the pen. But, the good thing, also can have the flaw! It doesn't, I in front of a classmate, the examination in the erasable pens, it's nothing, but he was rubbing test negative, positive word also to erase, and haven't noticed, the three points wronged points were in vain. What you say is irritating! If I were, I'd be pissed! Then I thought, the brush can be erased because of the heat generated by friction, if the hand can be erased in a very hot situation, the handwriting will not be restored in a very cold situation. So I went home and started the experiment: I wrote my name on a blank piece of paper, erased it, wrote my class on the erased name, and put the paper in the freezer. After about five minutes, I took out the paper and found that all the words I had written had appeared, and the names had overlapped with the class. It wasn't enough. I took another piece of paper, wrote my name on it again, poured boiling water into a clear plastic cup, and put the plastic cup on the word. After about four minutes, the words on the paper gradually disappeared. As it turned out, my guess was right! After this experiment, I almost never used a pen again. I took notes, homework and exams. Or if one is not careful, the consequences will not be... So, I personally think, can brush pen in study still use less good! Or else... Do you know!