Sheets of postage stamps are perforated.是什么意思？

Sheets of postage stamps are perforated.

一张张的邮票都打过接缝孔.

sheets

n. 纸( sheet的名词复数 )，被单，一张（通常指标准尺寸的纸），一大片（覆盖物）；

例句
He picked up the sheets of paper, and balled them tightly in his fists...
他抓起那几张纸，在手里紧紧攥成团。

of

prep. 关于，属于…的，由…制成；aux. 助动词 [非标准用语、方言] =have [主用于虚拟语气]；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

postage

n. 邮费，邮资；

例句
There's a postage and packing fee in addition to the repair charge.
除修理费之外还有邮寄和包装费。

stamps

n. 印( stamp的名词复数 )，邮票，跺脚，标志；

例句
Can I have a book of first class stamps please?
请给我一板第一类邮件的邮票好吗？

are

vi. （用于第二人称单复数现在时，第一、三人称复数现在时）是；n. 公亩（等于100平方米）；

例句
We are scared to abandon ourselves to our feelings in case we seem weak or out of control.
我们不敢放纵自己的情感，以免显得太过软弱或缺乏自制。

perforated

v. 穿孔于，在…上打眼( perforate的过去式和过去分词 )，（在纸张等上）打齿孔[孔眼线]；

例句
The ulcer has perforated into the lessor omental bursa.
溃疡穿透到小网膜囊.