背面有质感，不易留下大量的指印，不过可以清楚的看到手指触摸的位置。
The back has a textured feel that isn't massively fingerprint prone but you can definitely see where fingers have touched.
一种简单的方法是放一根干净的手指到你的口腔里，再到舌头的背面去刮一点唾液，然后涂到手背上，一分钟后再闻一闻。
A simple way is to stick a clean finger in your mouth and scrape saliva from the back of your tongue. Put it on the back of your hand, wait a minute, then smell your hand.
对于伸肌肉的拉伸，参照上述用一只手反向把手指推向另一只手手指的背面向前臂的底端压。
For stretching the extensor muscles, press the back of the fingers towards the bottom of the forearm.
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