Although the name sounds pretty serious, the condition typically 16 .
答案：(A) isn't
本句是省略句，isn't 後面省略了與前面重複的 serious：儘管名稱聽起來嚇人，這個症狀通常並不嚴重；doesn't、couldn't、wouldn't 都無法承接 be 動詞的省略。
答對率 34%。
空格後面直接是句號，你會覺得句子「沒寫完」，因而不敢選。其實這是省略：Although the name sounds pretty serious, the condition typically isn't (serious).——形容詞 serious 前面才剛出現過，第二次就省略掉，只留下 isn't。
省略掉的是形容詞 serious，而形容詞前面要配的是 be 動詞，所以只能用 isn't；doesn't、couldn't、wouldn't 後面該接原形動詞，接不上一個被省略的形容詞。「看到句尾只剩助動詞，先回頭找它省略掉的是什麼，再決定該用哪一種助動詞。」
國中的簡答就是同一回事：Are you tired?—Yes, I am (tired).／Do you like it?—Yes, I do (like it).。be 動詞的問句用 be 回答，一般動詞的問句用 do 回答，這裡只是把它放進一個敘述句裡。
Although…, …isn't.（省略重複的形容詞）、sound serious（聽起來嚴重）、that's not the case（並非如此）、a deficiency（缺乏症）。
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.