書名：疾天New Toeic閱讀超高分
版本：2019/7初版
頁數：p.49 第111題
題目：
Due to the high volume of foot traffic, the shop must polish its
floors more_______ than usual during the peak season.
(A) frequent
(B) frequented
(C) frequency
(D) frequently
疑問：為甚麼是D而不是A