By the time a child reaches age 21 years all 32 permanent teeth will usually have erupted.

当孩子到达年龄21年的时候全部32个恒牙通常恒牙萌发完成。

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By the time a child reaches age 21 years all 32 permanent teeth will usually have erupted.

当孩子到达年龄21年的时候全部32个恒牙通常恒牙萌发完成。

youdao