She folded up her letter, licking the envelopeflap with relish.
她把信折起来,享受地舔着信封盖。
《柯林斯英汉双解大词典》
2
The flap of the envelope had come unstuck.
信封的封口没粘牢张开了。
《牛津词典》
3
Please put the completed Form 26, together with any further reports required, into this envelope. Please seal it and place your signature or rubBer stamp over the junction of flap and envelope.