复数： envelopes

Inside the empty envelope propped up against a cup .

紧靠在杯子旁的那个空空的信封里面。

Anyway , he opens the envelope addressed to the new doctor and reads

总之，他拆开了那封写给新大夫的信，并读到了以下的句子：

The outer envelope of all four sections contains air maintained at atmospheric pressure .

四部分的外层封皮充满空气用来保持与大气的压力相协调。

Use her favorite color envelope .

要用她最喜爱的彩色信封。

The envelope could contain every secret she 's ever had .

那个信封里没准包含了她所有的秘密。