(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) the concept of social class
(2) concepts such as ‘civilization ’ and ‘government ’
(3) He can't grasp the basic concepts of mathematics.

(1) The hills were shrouded in mist .
(2) Early morning mist patches will soon clear.
(3) The origins of the story are lost in the mists of time (= forgotten because it happened such a long time ago) .

(1) The colleges grouped together to offer a wider range of courses.
(2) We all grouped around the tree for a photograph.
(3) The children grouped themselves around their teacher.

(1) We're open till 6 o'clock.
(2) Can't you wait till we get home?
(3) Just wait till you see it. It's great.

(1) I'd just like to make a comment...
(2) I made a few phone calls...
(3) Apparently he made a mess of his audition...

(1) an eye exam
(2) (North Amercian English)She did well on her exams .
(3) (British English)She did well in her exams .

(1) His singing can't hold a candle to Pavarotti's.
(2) The bedroom was lit by a single candle.
(3) Girls today can't hold a candle to the beauties of the Fifties.

(1) Speed is restricted to 30 mph in towns.
(2) We restrict the number of students per class to 10.
(3) Fog severely restricted visibility.

(1) The South african mailboat arrived on Friday mornings unless bad weather intervened.
(2) The South african president has negotiated an end to white-minority rule.
(3) The South african years were his most creative period.

(1) a ball made of rubber
(2) a rubber tree
(3) [常用于名词前]a rubber ball

(1) Jenny is seventeen years old.
(2) There are seventeen items on my shopping list.
(3) Texas , who died when my father was seventeen.

(1) a sharp knife
(2) sharp teeth
(3) a sharp drop in prices

(1) a fierce dog
(2) Two fierce eyes glared at them.
(3) He suddenly looked fierce.

(1) I want to be a goldfish.
(2) The pond contains a mixture of goldfish and carp.
(3) The Chinese kept and studied carp and goldfish more than one thousand years ago.

(1) She refuses to acknowledge the need for reform.
(2) a generally acknowledged fact
(3) I did not acknowledge that he had done anything wrong.

(1) The company is moving to new offices on the other side of town.
(2) Are you going to the office today?
(3) an office job

(1) a noble leader
(2) noble ideals
(3) He died for a noble cause.

(1) There will be a chance for parents to look around the school.
(2) Jeff deceived me once already─I won't give him a second chance .
(3) This is your big chance (= opportunity for success) .

(1) apple sauce
(2) a garden with three apple trees
(3) They really are apples and oranges.

(1) a corrupt regime
(2) corrupt officials accepting bribes
(3) corrupt practices

(1) Switch to an interest-paying current account and stay in credit. Most banks and larger building societies now offer these accounts...
(2) A steering committee has been formed. these people can make decisions in ten minutes which would usually take us months.
(3) Your camcorder should have these basic features: autofocus, playback facility, zoom lens...

(1) There is mounting tension along the border.
(2) international/racial/political tensions
(3) There is often a tension between the aims of the company and the wishes of the employees.

(1) That may or may not be true.
(2) We may have some rain today...
(3) Rates may rise, but it won't be by much and it won't be for long...

(1) an iron gate
(2) He pushed open the garden gate.
(3) A crowd gathered at the factory gates.

(1) His role has always been ambiguous.
(2) an ambiguously worded agreement
(3) an ambiguous word/term/statement

(1) ‘Is this your car? ’ ‘yes, it is. ’
(2) ‘Are you coming? yes or no? ’
(3) ‘I enjoyed her latest novel. ’ ‘yes, me too. ’

(1) I couldn't stop coughing.
(2) to cough nervously/politely/discreetly
(3) Sometimes she coughed (up) blood.

(1) She usually sings in the shower.
(2) I just can't sing in tune!
(3) He was singing softly to the baby.

(1) I always associate the smell of baking with my childhood.
(2) He is closely associated in the public mind with horror movies.
(3) I don't like you associating with those people.

(1) flowers that bloom in spring/in the spring
(2) He was born in the spring of 1944.
(3) There's a feeling of spring in the air today.

(1) Did you have a good trip?
(2) We went on a trip to the mountains.
(3) a day trip (= lasting a day)

(1) The area was covered in dense jungle.
(2) the jungles of South-East Asia
(3) jungle warfare

(1) Can I have a receipt, please?
(2) to make out (= write) a receipt
(3) to acknowledge receipt of a letter

(1) She was chatting away, nineteen to the dozen.
(2) They have nineteen days to make up their minds.
(3) It's nineteen hour Beijing time.

(1) The furniture comes complete with tools and instructions for assembly.
(2) We were in complete agreement.
(3) a complete change

(1) the rumble of distant thunder
(2) a clap/crash/roll of thunder
(3) thunder crashed in the sky.

(1) newly independent republics
(2) the republic of Ireland
(3) In 1918, Austria became a republic.

(1) a large circle of friends
(2) Seagulls circled around above his head.
(3) The plane circled the airport to burn up excess fuel.

(1) In some countries children don't start learning to read and write until they are six.
(2) Please write in pen on both sides of the paper.
(3) I haven't got anything to write with.