Collaboration

Collaboration comes from the verb collaborate (= work in partnership with someone on the same task, especially one of a scientific, artistic or industrial nature) or act of working jointly: ‘He was one of the scientists who had collaborated with Oppenheimer to produce the first atomic bomb.’

Classic

Classic = being among the best or most typical of its class; serving as a standard or model: ‘The painting is a classic example of sixteenth century Venetian art.’

Classical music = the music of Mozart, Beethoven, etc. ‘I prefer classical music to rock.’

Circumstance

Circumstance is nearly always used as a plural noun (WITH s) = A condition that accompanies or influences some event or activity: ‘The police are investigating the circumstances surrounding his death.’ ‘Under normal circumstances, I would never have left my passport with a stranger.’

Choose

Choose between two (or a few) possibilities: ‘You have to choose between a beginner’s course and a more advance course.’

Make a selection from a large number of alternatives: ‘When it comes to wallpaper, there are hundreds of different patterns to choose from.’

Choose sb/sth (WITHOUT for): ‘The roses were too expensive so I choose the daffodils.’

Certificate

Certificate = an official document that states certain facts about someone: ‘A birth/marriage/death certificate’, ‘A certificate of health.’

Voucher = a kind of ticket that can be used instead of money: ‘a gift/luncheon/travel voucher.’

Change

(1)Make different; cause a transformation: ‘The discussion has changed my thinking about the issue.’(2)Undergo a change; become different in essence; losing one's or its original nature: ‘She changed completely as she grew older.’ ‘The weather changed last night.’ (3)Become different in some particular way: ‘Her mood changes in accordance with the weather.’(4)When you mean that someone or something is now different in some way, use change in: ‘The Prime Minister has made several changes in the Government.’

Catch up

Catch up (on/with sth) = do the things that you should have done before so that your work is up to date: ‘Why don’t you stay at home tonight and catch up on some of your homework?’