Examples:

• 'U'

• undertake to : The new government undertook to  reduce personal income tax.
• unite behind : The leader called upon the people to unite behind  him to deter foreign aggression.
• urge on : Urged on  by his supporters, he ran the fastest race of his life.
• use up : Someone has used up  all my discs.
• usher in : There were fireworks and people were reveling to usher in  the new year.

• ---

  'V'

• value at : His wealthy uncle bought paintings valued at  over $300,000.
• vary from : As a street vendor, his takings vary from  day to day.
• veer off : The car veered off  the road into a ravine.
• verge on : Her extreme anxiety at times verges on  a nervous breakdown.
• vie in : John and Johnny have been vying in  the same contest for the past four years.
• vie for : Only three contestants vied for  the top prize.
• vouch for : His long-time friend vouched for  him in his application for a new license.
• vote on : As the men couldn't agree on the most beautiful lady, they decided to vote on  it.
• vow to : She vowed to  devote the rest of her life to caring for the poor.
• vaccinate against : Nowadays children are vaccinated against  a variety of diseases.

• ---

  'W'

• wager on : Bob wagered  one hundred dollars on  the white horse.
• wait for : They waited  in vain for  her to turn up.
• wait on : She waits on  customers with utmost courtesy and patience.
• wait up : Sean waits up  for her every night.
• warn about : I warned  the kids  about  the danger of playing with fire.
• warn against : I was warned against  buying the house which was supposedly haunted.
• warn of : They warned  us of  the risks involved in investments in stocks and bonds.
• wash down : We had venison steak washed down  with red wine.
• wash off : Robert washed  the dirt and dust off  the wall before painting it.
• wash out : The match was completely washed out  by the unexpected weather.
• wash up : The carcass of a whale was washed up  the beach.
• watch for : We watched  the screen for  the flight schedules.
• weed out : Those not so physically fit were the first to be weeded out .
• whisk away : The police arrested the suspect and whisked him  away in the police car.
• wipe out : The recent earthquake wiped out  the entire village.
• wish for : I wish for  the luck to strike the lottery jackpot.
• withdraw from : She withdrew from  the beauty contest due to death threats made against her.
• work for : She was told that she had been working for  a crook.
• work off : Janet always uses swearing words whenever she tries to work off  her anxiety.
• work on : Tommy spent weeks working on  the sculpture.
• work out : The burglars have worked out  how they're going to sneak into the whisky warehouse.
• work up : I certainly worked up  a big appetite after a marathon jog.
• work with : I find it utterly impossible to work with  her unless she changes her attitude.
• worry about : She worries  more about  me than I worry about her.
• worry over : I habitually worry over  the slightest thing.
• write back : I've written her ten letters in the past weeks, but she has not written back .
• write down : You don't have a good memory, so you'd better write down  whenever you need to.
• write in : Hundreds of viewers wrote in  to complain after the show.
• write out : He couldn't speak due to a bad sore throat, so he wrote  it out  instead.
• write up : Each one of us had to write up  a report on human rights for the meeting.

• ---

  'Y'

• yank on : He kept yanking on the dog's tail and before long he was bitten.
• yearn for : Joan yearns for  Mr. Right to appear.
• yearn to : He couldn't get used to life in a boarding school and every day he yearned to  go home.
• yell at : They yelled at  him not to get into the bullring.
• yield to : The victim's family agreed to yield to  the kidnappers' demand for ransom.