19 the source of the injury, these spots typically do not require any treatment and should go away as your nail grows out.
答案：(C) Whatever
【連接詞】Whatever the source of the injury 表示「無論受傷原因為何」，為讓步子句，其後省略 be 動詞 is。Supposing（假設）、Including（包括）語意不合；Whether 通常需搭配 or not 或子句動詞，不符此處省略句構。
Supposing、Including、Whatever、Whether 四個排在一起，其中兩個是 -ing 形，你很容易先認定這是分詞的題目，開始找意義主詞、分主動被動。選項的排列方式本身就是陷阱，這一題根本不走分詞那條路。
先看空格後面接的是什麼。空格後是 the source of the injury 這個名詞片語，接著一個逗號，再接完整的主要子句 these spots typically do not require any treatment…。也就是說，空格帶的這一串裡沒有動詞，能放進這個位置的只有可以省略 be 動詞的讓步結構：Whatever (is) the source of the injury（無論受傷的原因是什麼）。省略主詞與 be 動詞這一招，就是課本教過的 While (he was) walking home。驗算法很簡單：把 Whatever 換成 No matter what 讀一次，語意完全成立。另外提醒一個落差：whatever 你的印象大概只有它單獨當代名詞用的「隨便、無所謂」（Whatever you say.），其實它也可以直接掛在名詞前面，意思是「無論哪一個」。鑑別度只有 34，吃虧的反而是文法練得熟的人：看到兩個 -ing 排在一起就進了分詞的程序，找不到動詞就把 Whatever 排掉，繞一大圈回到原點。
Supposing（假如）等於 if，後面要接完整的子句（Supposing it rains, what will we do?），本題沒有動詞可接。Including（包括）確實已經整組轉成介系詞、後面接名詞沒錯，但語意會變成「包括受傷的原因在內」，與主要子句「不需要治療」接不起來。Whether 要嘛接 or not、要嘛接 A or B、要嘛帶一個子句，單獨接一個名詞片語不成立。
whatever ＋ 名詞（無論哪一個…）、no matter what（無論什麼，與 whatever 可互換）、go away（消失、痊癒）、grow out（長出來）、require treatment（需要治療）、supposing（假如，等於 if）
Many people at some point in life have white spots on their fingernails. One of the most common causes for these little white spots is a condition called leukonychia. Although the name sounds pretty serious, the condition typically 16 . And while many people think the white spots are caused by a calcium or zinc deficiency, that's generally not the case.
In reality, these spots most often develop 17 mild to moderate trauma to your nail. If you can't think of anything that would have injured your nail, consider the fact that nails grow very slowly, so the injury 18 weeks before the spots ever appeared. The spots could also be a sign of a mild infection or allergy, or a side effect of certain medications.
19 the source of the injury, these spots typically do not require any treatment and should go away as your nail grows out. And they should not return unless you suffer another injury to a nail. However, this generally 20 when only a single or a few nails are affected. If all of your nails are showing white spots, the leukonychia could be related to another more serious condition such as anemia, cardiac disease, diabetes, or kidney disease.