This can be done by soaking sheets of newspaper in water for two hours and then 17 them into small pieces.
答案：(C) tearing
by soaking...and then tearing...，前後動名詞並列對等（both follow by），tearing 呼應前面的 soaking，維持句子結構一致。tear（原形）、tore（過去式）、torn（過去分詞）都不能接在 by 之後跟 soaking 並列。
四個選項是同一個字 tear 的四種形態，你會直覺開始分主動被動、找意義主詞。
這一格靠並列結構就定得下來。and 連的是空格前的 soaking sheets of newspaper in water 與空格這一串，兩邊都掛在句首那個 by 底下——by ＋ 動名詞（藉由做某事）。既然 and 前面是 soaking（動名詞），後面就必須是同樣形態的 tearing，兩邊才對得齊。填進去讀成 by soaking sheets of newspaper in water for two hours and then tearing them into small pieces（先把報紙泡水兩小時，然後撕成小片）。並列結構最省力的地方就在這裡：只要認出 and 連的是哪兩樣，形態直接照前面那一個抄。鑑別度只有 29，但它本身不難：介系詞後面接動名詞、and 前後形態要一致，這兩點都是課本教過的，各種程度的人都答得出來，題目自然分不出高低。
tear 是原形、tore 是過去式，兩個都不能接在介系詞 by 後面；torn 是過去分詞、表被動，但撕報紙的是人、報紙是被撕的那一方，這裡要的動作方向是主動。
by ＋ V-ing（藉由做某事）、and 前後形態一致（並列結構的基本要求）、tear A into pieces（把 A 撕成碎片）、soak A in water（把 A 泡在水裡）、be compressed into（被壓縮成）、tear down（拆除）。
If old newspapers are stacking up in your house, there are options other than tossing them out or selling them to a recycler.
Some environmental scientists suggest turning newspapers 16 charcoal. This can be done by soaking sheets of newspaper in water for two hours and then 17 them into small pieces. These pieces are then compressed into balls. After the water is 18, the ball-shaped pieces are put under the sun to dry before they can be used as a firewood or charcoal substitute.
19 suggestion made by the experts is to dip newspaper sheets in vinegar and water, and use them to clean windows, mirrors, and tiles. Old papers can 20 be used to line rubbish bins and as packing material when mailing breakable goods.