(1) Certain courses are compulsory, others are optional.
(2) This model comes with a number of optional extras (= things you can choose to have but which you will have to pay extra for) .
(3) A holiday isn't an optional extra. In this stressful, frantic world it's a must...

(1) a wealthy nation
(2) The couple are said to be fabulously wealthy.
(3) They live in a wealthy suburb of Chicago.

(1) speaking in hushed/low/clipped/measured, etc. tones
(2) a conversational tone
(3) a tone of surprise

(1) A lack of qualifications can be a major obstacle to finding a job.
(2) So far, we have managed to overcome all the obstacles that have been placed in our path.
(3) The area was full of streams and bogs and other natural obstacles.

(1) A neon sign flashed on and off above the door.
(2) Lightning flashed in the distance.
(3) You can go for a 'rostrum' system, which sounds flash, but can be assembled quite cheaply.

(1) An active volcano may erupt at any time.
(2) a dormant volcano (= one that is not active at present)
(3) an extinct volcano (= one that is no longer active)

(1) They drove away slowly to avoid arousing suspicion.
(2) He was arrested on suspicion of murder.
(3) I have a sneaking suspicion that she's not telling the truth.

(1) economic/social/political trends
(2) There is a growing trend towards earlier retirement.
(3) current trends in language teaching

(1) to release a prisoner/hostage
(2) Firefighters took two hours to release the driver from the wreckage.
(3) He refused to release her arm.

(1) The car braked and swerved.
(2) The truck braked to a halt .
(3) You don't need to brake at every bend.

(1) a valid passport
(2) a South African passport
(3) I was stopped as I went through passport control (= where passports are checked) .

(1) strategic planning
(2) a strategic decision to sell off part of the business
(3) Cameras were set up at strategic points (= in places where they would be most effective) along the route.

(1) to maintain law and order/standards/a balance
(2) The two countries have always maintained close relations.
(3) (formal)She maintained a dignified silence.

(1) Dirty streets and homelessness are no advertisement for a prosperous society.
(2) Put an advertisement in the local paper to sell your car.
(3) Miss Parrish recently placed an advertisement in the local newspaper.

(1) It was only a partial solution to the problem.
(2) a partial eclipse of the sun
(3) I'm not partial to mushrooms.

(1) He's got no right to keep dumping his problems on me.
(2) Just dump your stuff over there─we'll sort it out later.
(3) Did you hear he's dumped his girlfriend?

(1) a lunar eclipse/landscape
(2) The vast volcanic slope was eerily reminiscent of a lunar landscape.
(3) ...a magazine article celebrating the anniversary of man's first lunar landing.

(1) She slipped over on the ice and broke her leg.
(2) As I ran up the stairs, my foot slipped and I fell.
(3) His hat had slipped over one eye.

(1) The peasants arose against their masters.
(2) Are there any matters arising from the minutes of the last meeting?
(3) Several new industries arose in the town.

(1) I need to pay off all my debts before I leave the country.
(2) an outstanding debt of £300
(3) He had run up credit card debts of thousands of dollars.

(1) stale cigarette smoke
(2) stale sweat
(3) stale jokes

(1) A disastrous business venture lost him thousands of dollars.
(2) They ventured nervously into the water.
(3) He's never ventured abroad in his life.

(1) She jabbed him with her elbow.
(2) He's fractured his elbow.
(3) The jacket was worn at the elbows.

(1) the vitamins that are vital for health
(2) Good financial accounts are vital to the success of any enterprise.
(3) It is vital that you keep accurate records when you are self-employed.

(1) Parents are obliged by law to send their children to school.
(2) I felt obliged to ask them to dinner.
(3) He suffered a serious injury that obliged him to give up work.

(1) Clint is awful smart.
(2) the awful horrors of war
(3) [不可数名词]the sheer awfulness of the situation

(1) My school did nothing whatsoever in the way of athletics...
(2) I don't think they'll have any idea how I'm feeling. None whatsoever...
(3) However, NIBCO ? does not assume any liability whatsoever for the accuracy or completeness of such information.

(1) a valid passport
(2) a bus pass valid for 1 month
(3) They have a valid claim to compensation.

(1) One liter of water was added, and the solution was left at 4 oC overnight.
(2) The guide disguised his guilty of mixing the liquor width a liter of liquid.
(3) The capacity of this bottle is one liter.

(1) to put sth on temporary/permanent display
(2) The exhibition gives local artists an opportunity to display their work.
(3) She displayed her bruises for all to see.

(1) The council has committed large amounts of money to housing projects.
(2) She was committed to a psychiatric hospital.
(3) She committed the instructions to memory.

(1) The new drug has not yet been licensed in the US.
(2) (British English)licensing hours (= the times when alcohol can be sold at a pub, etc.)
(3) They had licensed the firm to produce the drug.

(1) The exhibition has stimulated interest in her work.
(2) The article can be used to stimulate discussion among students.
(3) Parents should give children books that stimulate them.

(1) a shortfall in tax revenue
(2) a slump in oil revenues
(3) The company's annual revenues rose by 30%.

(1) Someone had forged her signature on the cheque.
(2) They collected 10 000 signatures for their petition.
(3) He was attacked for having put his signature to the deal.

(1) The hotel was really filthy and I'm not exaggerating.
(2) He tends to exaggerate the difficulties.
(3) I'm sure he exaggerates his Irish accent (= tries to sound more Irish than he really is) .

(1) He said he would appeal after being found guilty on four counts of murder.
(2) The company is appealing against the ruling.
(3) The prospect of a long wait in the rain did not appeal.

(1) Such problems are a universal feature of old age.
(2) Agreement on this issue is almost universal.
(3) universal suffrage (= the right of all the people in a country to vote)

(1) Much of the meaning must be inferred from the context.
(2) It is reasonable to infer that the government knew about these deals.
(3) Are you inferring (that) I'm not capable of doing the job?

(1) His speech was a powerful spur to action.
(2) I phoned him up on the spur of the moment.
(3) a spur-of-the-moment decision