非高峰时间电话费每单位两角。

Phone calls cost 20c per unit off-peak.

《牛津词典》

也就是能够分开两个距离很近的两颗星的能力，单位是角秒1(seconds of arc)。

It is the ability to separate two closely-spaced stars into two distinct images measured in seconds of arc.

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之后，除去多余材料，我用单位，全面和三角档案顺利的边缘。

After removing the excess material, I used flat, round and triangle files to smooth the edges.

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