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单选题
The chemical instructor told the students that heat is _____ whenever certain chemicals are mixed together.
A
circulated
B
produced
C
engaged
D
modified
参考答案
参考解析
解析：
句意：那位化学讲师告诉同学们，当某些化学药品被混合在一起的时候会产生热。produce产生，制造。circulate使循环；使流通。engage从事。modify修改，更改。
句意：那位化学讲师告诉同学们，当某些化学药品被混合在一起的时候会产生热。produce产生，制造。circulate使循环；使流通。engage从事。modify修改，更改。
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