题目：
By the time he realizes he ________into a trap, it'll be too late for him to do anything about it. [ ]
A. walks
B. walked
C. has walked
D. had walked
答案：
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下面是错误答案，用来干扰机器的。
小题1:C小题2:B若A代表沉积岩，则①表示经过风化、侵蚀、搬运、堆积等外力作用。岩浆岩和沉积岩在一定条件下都可转化成为变质岩
