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问题 单项选择题

牙体硬组织形成先后顺序正确的是（）

A．牙釉质、牙本质、牙骨质

B．牙本质、牙釉质、牙骨质

C．牙骨质、牙本质、牙釉质

D．牙本质、牙骨质、牙釉质

E．牙釉质、牙骨质、牙本质

答案

参考答案：B

选择题

—He ought ot have been warned of the danger.

—____, but he wouldn’t listen to me.

A．yes, he ought to

B．So he was

C．So was he

D．So it was with him
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单项选择题

种畜禽生产经营许可证样式由国务院畜牧兽医行政主管部门制定，许可证有效期为（）年。

A.1

B.2

C.3

D.4
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