ADJ

major
minor, small
life-saving, vital
emergency
routine
delicate
a delicate eye operation
exploratory
surgical, transplant
heart, knee, etc.

VERB + OPERATION

have, undergo
He had an operation to remove a tumour
come through, survive
She came through the operation very well
carry out, perform
the surgeon performing the operation

PREP

during a/the ~
She woke during the operation
~ for
an operation for a kidney problem
~ on
a major operation on his heart

ADJ

big, large-scale, major, massive
covert, undercover
combined, joint
tricky
a tricky rescue operation
intelligence, military, naval, police
guerrilla
clean-up, drilling, mining, mopping-up, offensive, peacekeeping, relief, rescue, salvage, security
UN troops supervised the relief operations
banking, building, business
restrictions placed on business operations

VERB + OPERATION

begin, launch, mount, undertake
The authorities launched a massive security operation in the city
carry out, conduct
supervise

PREP

during a/the ~
during joint military operations

PHRASES

a theatre of operations (= where military operations take place)

ADJ

effective, efficient, smooth
day-to-day
the smooth day-to-day operation of the department

VERB + OPERATION

come into
A ceasefire came into operation in May
bring/put sth into
cease
The factory will cease operation at the end of the year

PREP

during ~
The machine can get very hot during operation
in ~
The current tax system has been in operation for ten years

PHRASES

in/into full operation
the only reactor in full operation