題目
Beardshaw’s did very well _____ the economy was booming, but when a recession came, it saw sales fall dramatically. (A) during (B) for (C) while (C) when
答案是c
我知道while 和 when區別是看後面動詞是否加ing,但看到這題我直覺是a
我上網找during 和while差別也覺得答案應該是a (while應該是省略主詞)
請問是答案有誤，還是我哪裡理解錯了