The middle button of his uniform jacket was strained over his belly.

他制服上衣中间的那个扣子在他的肚子上绷得紧紧的。

《柯林斯英汉双解大词典》

Because window managers can differ, as can hardware (you might not even have a mouse with a middle button), these instructions are not as hard and fast as you might need.

因为窗口管理器和硬件可能有所不同，甚至可能没有鼠标中键，所以这里的说明可能与您所需要的并不完全相同。

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The middle button of his uniform jacket was strained over his belly .

制服上装中间的纽扣在他的肚子上绷得紧紧的。

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On the right, the top and bottom buttons scroll up and down and the middle button selects.

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Rolling the middle button up results in a piercing attack while rolling it down gives you a downward slash.

FORBES: Move up http://i.forbesimg.com t Move down

Also, the center Select button, in the middle of the directional arrows, is a bit hard to use, as the circle button is quite small.

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