The semester exam is coming, and he vowed to concentrate on his lessons and stop dozing off. So I always drink coffee every day and slap myself when I fall asleep. But none of these works very well. I'm still sleepy in class. Suddenly one day, he became energetic in class, and even when he was sleepy, he soon picked up his energy and threw himself into learning. I was puzzled. When I asked him how he did it, he mysteriously told me the way to avoid drowsiness. Whenever he was sleepy, he stroked his little brother, and his little brother quickly swelled several times, eager to try, and his spirit followed, and he quickly entered the learning state again. I can't help feeling that his performance can firmly take the first place in the class, and his little brother really contributes a lot.

It turns out that the little brother has such a function. Although it can not be inserted into the earth when it is big, it is indispensable to learn when it is small!