may; might; perhaps; may be; possibly
in case of; at that time; at this time
separation; isolation; extrication; release; isolation
flow (of a fluid or gas); stream; flow (of people, things); passage (of time); course (of events); (step-by-step) procedure; group of people who remain together after the end of an event
(heavy) drinker; drunkard; tippler; boozer
weak; frail; delicate; tender; unskilled; weak (wine)
measure; step; dealing with; medical treatment
Second World War (1939-1945); World War II; WWII; WW2
German Air Force; Luftwaffe
allied forces; the Allies (e.g. in WWII)
postwar period; period after Second World War
source of protein; protein source
culture medium; growth medium
infiltration; permeation; exudation; percolation; effusion; extraction
sulfurous acid; sulphurous acid
riddle; puzzle; enigma; enigmatic; mysterious
abrupt; sudden; unexpected
free (of restraint, controls, etc.); free (of cost); freelance; one-size
sales; selling; marketing
suspension; stoppage; discontinuance; interruption
to be at a loss; to be puzzled
to abandon; to fail; to desert; to forsake
mundane; routine; everyday; unremarkable; common; day-to-day
soil; breeding ground; fertile ground (for); foundation (for the development of ...)
clue; lead; key; handhold; hold
to make a breakthrough; to break ground
breakthrough (research, etc.); breach; opening