A packet of envelopes的用法和样例：
- She bought a packet of envelopes at that shop.
- I have a coupon for ten pence off a packet of soap.
- She bought a packet of envelops at the stationery store.
- She bought a packet of shaved ham.
- He sent the waiter for a packet of cigarettes.
- Oliver filched a packet of cigarettes from a well-dressed passenger.