题目内容

Select proper words to fill in the blanks.conserve, preserve, reserve, deserve1.We are ______________ these seats for my parents.2.Effective measures must urgently be taken to ___________ these endangeredspecies of wild animals.3.To ______________ a friend, three things are required: to honor him when present, praisehim when absent, and assist him in his necessities.

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Match the phrases with correct Chinese meaning.

弧面型宝石一般使用()。

A. 硬盘抛光
B. 软盘抛光
C. 滚筒抛光
D. 振动抛光

加工的宝石表面出现“镜面效应”,磨粒磨削深度一般为()。

A. 10nm
B. 30nm
C. 50nm
D. 100nm

宝石的抛光机理比较复杂,现有三种学说比较流行:微粒机械磨削学说、流布学说及物理化学学说。

A. 对
B. 错

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