问题
选择题
From time to time a crocodile has snatched someone _______ he or she is even aware that the crocodile is there.
A．when
B．until
C．since
D．before
答案
答案：D
考查时间状语从句。句意“有时候，在人们意识到有鳄鱼之前，鳄鱼会突然捉住他。”A“当”；B“直到”；C“自从”；D“在......之前”。故选D。