Pitchers were forbidden to give the ball an artificial spin or trajectory by, for instance, nicking it or spitting on it and from discolouring the ball with dirt or tobacco juice or hair grease.
In general, I discourage use of hair dyes containing artificial coloring agents, which to my mind are as suspect in cosmetic products as they are in food.
总体来说，我不赞成使用带有人工色素染剂的染发剂，对于我来说，对化妆用品的不可信就像对食物中一样。
3
Shi and Li's artificial polymer tubules have a diameter of around 50 microns - about half the width of a human hair.