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题目内容
（河北农业大学大学英语Ⅳ）
As urban populations exported finished goods _______ raw materials from neighboring populations, organized trade grew substantially.
A、
exchange for
B、
in exchange for
C、
are at exchange for
D、
to be the exchange for
A、
exchange for
B、
in exchange for
C、
are at exchange for
D、
to be the exchange for
参考答案
