under cover

形容词 under cover:

1. conducted with or marked by hidden aims or methods
   同义词：clandestine, cloak-and-dagger, hole-and-corner, hugger-mugger, hush-hush, secret, surreptitious, undercover, underground

1. The soldiers crept forward under cover of darkness.
   士兵在夜色的掩护下匍匐前进。
2. He kept his invention under cover until it was patented.
   在取得专利权以前，他的发明一直秘而不宣。
3. Crimes committed under cover of patriotism.
   打著爱国的旗号犯下的罪行。
4. We travelled under cover of darkness.
   我们在夜幕掩护下行进。