“封皮”怎么读

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这包裹的封皮扯不开.The cover of the parcel won't tear.我廉价买下了它,因为它的封皮坏了.I got it cheaply as its cover was torn.赫伯尔特用铅笔在一本书的封皮里边写了些什么.Herbert had been writing with his pencil in the cover of a book....