invert center meaning in English

翻转中心

The collector ' s heart stood still as he saw that the sheet while been offered him had inverted centers
当这个集邮者看到邮票时他的心跳霎那间停顿了，给他的这版邮票有一个倒转的中心。
The collector ' s heart stood still as he saw that the sheet , which had been offered him , had inverted centers
当这个集邮者看到邮票时他的心跳刹那间停顿了，给他的这版邮票有一个倒转的中心。
Excited by his find , obey shopped other branch post offices for more sheets with inverted centers but found none
罗比被他的发现振奋，他到其它邮政支局去寻购更多张“倒转”邮票，但是毫无结果。
Excited by his find , robey shopped other branch post office for more sheets with inverted centers but found none
罗比被他的发现振奋，他到其它邮政支局去寻购更多张的“倒转”邮票，但是毫无成果。