People pass, black and white, the Negroes frankly participants in the spirit of Spring, the whites laughing constrainedly, awkward in natural emotion.

穿梭而过的行人中有黑人也有白人，黑人自在地享受着美好的春光，白人们则强作欢笑，表情显得不自然。

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This paper introduces several typical structures of HCB and expatiate on the principle of naturally current commutating and constrainedly current commutating.

介绍了几种混合式断路器的典型结构，阐述了自然换流和强制换流的原理。

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And the antifriction bearing (18) is radially and constrainedly installed through a pressing cooperation, thereby the ball (25) no longer jump out of the bearing (18).

减摩轴承(18)通过压配合被径向约束地安装，使得滚珠(25)能够不再跳出轴承(18)。

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And the antifriction bearing (18) is radially and constrainedly installed through a pressing cooperation, thereby the ball (25) no longer jump out of the bearing (18).

减摩轴承(18)通过压配合被径向约束地安装，使得滚珠(25)能够不再跳出轴承(18)。

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