题目内容
Enamel(牙釉质) is ______ thing in the human body and keeps bacteria(细菌) away.
A) hard B) harder C) hardest D) the hardest
D
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Enamel(牙釉质) is ______ thing in the human body and keeps bacteria(细菌) away.
A) hard B) harder C) hardest D) the hardest
D
习题精选系列答案