under plain cover / under separate cover

under plain cover / under separate cover if a letter etc is sent under plain cover or under separate cover, it is sent in a plain envelope or a separate envelope放在普通信封里/在另函内:•The bill will be sent to you later under separate cover.账单稍后另函寄上。

• physical geography
• mercury sulfate
• think good to do something
• con man
• retinoschi sis
• solar coalition
• Acanthodii
• goldenrod
• do sb out of
• chairmanships
• drabbest
• play it straight
• chapping
• reversal spectrum
• the operative word
• 'sdeath
• buy at
• DNA sequencing
• breadboard model
• nerve-end
• basic dyes
• freetrade
• enormousnesses
• big as a barn door
• spurious response
• keep up heart
• splint-bottomed
• proctoclyses
• Stenocephalidae
• technical market analysts
• muddlehead
• be on/upon one’s legs
• mass transport
• resentest
• caucasoids
• switching power supplies
• be out from
• plough on (with sth)
• do the best one can
• stretchier
• fibrinolyses
• phase-locked loop
• squireless
• intellectualiser
• go about
• reflector satellite
• cyproterone acetate
• gap lathe
• shrouds
• phyllode
• bioengineers
• jellying
• from day one
• accordantly
• drag the name of someone（或something）through the dirt
• wreckest
• tansformationalgenerative grammar
• differential amplifier
• quadrennial
• flat-hatted
• headfish
• ligatured
• whorled
• equity-linked bank deposits
• toxoprotein
• hero worships
• power traverse
• scrapyard
• cablecaster
• raintight
• plum cake
• give due / full weight to
• squabbish
• derisible
• rubberised
• eviler 或 eviller
• pound the books
• average molecular weight
• Vaneyellidae
• misbestow
• on tiptoe（或tiptoes）（〈北美〉 亦作on one's tiptoes）
• bronchoscopy
• faith headling
• jury-rigging
• roadhouse
• monometric
• singa bility
• have a few
• exhortatively
• owe sb an explanation / apology
• teleobjective
• Entelodontidae
• Inchon
• Old Tom
• plaster
• potato masher
• S. and M.
• squabs
• ebracteate
• sb's energies