書名：14黃金認證 NEW TOEIC 新多益閱讀題庫解
頁數：126
題目：On the first day of the class,the lab instructor demonstrated safety
procedures and warned everyone to be ___ when working with dangerous
chemicals.
(A)caution
(B)cautious
(C)cautiously
(D)cautiousness
疑問：把C刪除後，但是剩下的3個選項該怎麼考慮
答案是B