The way paper tears is related directly to how it is made. Most paper is made from wood fibers. Logs are chopped into wood chips, mixed with water and chemicals, and run through a process that separates the wood fibers. The soupy mush that results is called pulp. The pulp is pressed onto a mesh conveyor belt that squeezes the water out. As the pulp moves along the belt, the wood fibers line up in the direction of the belt’s travel. This alignment of the fibers on the belt gives the paper a grain. This grain is what causes the paper to tear straighter one way than the other. When paper is ripped with the grain, the tear goes with the direction of the fibers, and is fairly straight. When you tear the paper across the grain,the tear tends to wander as it works against the direction of the fibers.

【生詞注釋】
tear n. 撕
chop v.砍，劈
mush n.軟糊狀的東西
pulp n. 紙漿
alignment n.排列
grain n. 成粒狀

【參考譯文】
撕紙的方式直接同紙張的制作緊密聯系。大多數紙都是由木纖維制成的。木頭被砍成木片，同水和化學物質一起攪拌，經過一種流程將木纖維分開。產生的漿糊狀的物質叫做“紙漿”。 紙漿再在網狀的傳送帶上擠壓，將水擠出來。隨著紙張在傳送帶上移動，木纖維會向著傳送帶的方向排列。纖維在傳送帶上的排列會使紙張成粒狀。這種粒狀會使紙張在撕裂時在一個方向比另一個方向撕得直。當紙張順著粒狀撕時，撕的方向和木纖維的方向相同，撕得就會很直。當你從粒狀中間撕紙時，因為撕的方向和木纖維方向相反，撕得就會彎曲些。