書名：OG Vol.4
頁數：p.314 #120
題目：
By the time the magazine articel on home security devices ___ on the
newsstands, the pricing information was already outdated.
A) appears
B) appared
C) will appear
D) appearing
疑問：答案是B
請問"By the time" 可以當作是副屬連接詞嗎? 是不是同等於"Before"
目前卡關的原因是把"By"當介係詞,因此選的是動狀詞D! Thanks!