书名：OG Vol.4
页数：p.314 #120
题目：
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newsstands, the pricing information was already outdated.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
疑问：答案是B
请问"By the time" 可以当作是副属连接词吗? 是不是同等于"Before"
目前卡关的原因是把"By"当介系词,因此选的是动状词D! Thanks!