Margaret Thatcher on her way to Buckingham Palace to inform the Queen of her resignation 1990: Thatcher quits as prime minister England have Margaret Thatcher is to stand down as prime minister after her Cabinet refused to back her in a second round of leadership elections. She will remain in office until a successor is elected, but will not continue to fight Michael Heseltine for the Conservative Party leadership. The former secretary of state for the environment threw down the gauntlet after a string of serious disputes over Britain's involvement in the European Union. The prime minister said pressure from colleagues had forced her to conclude that party unity and the prospect of victory in the next general election would be better served if she stepped down. Downing Street issued a statement at 0930 GMT after Mrs Thatcher had informed her Cabinet and the Queen of her intention. By 1200 GMT, Chancellor John Major and Foreign Secretary Douglas Hurd had announced they would now stand against Mr Heseltine in the next stage of the leadership contest. The decision comes less than 24 hours after the Iron Lady had vowed to "fight on and fight to win" after winning the first round - but not with the required majority. Tory Party Chairman Kenneth Baker said it was a typically brave and selfless decision from the prime minister. "Once again Margaret Thatcher has put her country's and party's interests before personal considerations," he said. And there were tributes to Mrs Thatcher from both sides of the House of Commons during Prime Minister's Questions. Labour leader Neil Kinnock said the prime minister's decision showed she amounted to more than those who had recently turned against her. But the outgoing Tory leader refused a request from Mr Kinnock to hold a general election so the British people could make their own choice about her successor.

Kennedy's car sped off after he was shot 1963: Kennedy shot dead in Dallas Artificially 1969: The The President of the United States has been assassinated by a gunman in Dallas, Texas. John F Kennedy was hit in the head and throat when three shots were fired at his open-topped car. The presidential motorcade was travelling through the main business area of the city. Texas Governor John Connally was also seriously injured when one of the unknown sniper's bullets hit him in the back. The men were accompanied by their wives, who were both uninjured. Vice-president Lyndon Johnson - who was following in a different car - has been sworn in as the new US leader. The presidential party was driving from Dallas airport to the city centre when witnesses said shots were fired from the window of a building overlooking the road. The president collapsed into Jackie Kennedy's arms, who was heard to cry "Oh no". Seconds later Governor Connally was also hit. Dallas Times Herald photographer Bob Jackson was in the motorcade close behind the Democrat leader's car and heard the shots as it entered Dealey Plaza. "As I looked up I saw a rifle being pulled back from a window - it might have been resting on the windowsill - I didn't see a man," he said. Mr Kennedy's limousine was driven at speed to Parklands Hospital immediately after the shooting. The president was alive when he was admitted, but died at 1400 local time (1900 GMT) - 35 minutes after being shot. Police and Secret Service agents stormed the School Book Depository building moments after the shots were fired and recovered a rifle with a telescopic sight, said to be the assassination weapon. The mood of shock in the US was echoed by Senator Mike Mansfield in an emergency forum of the senate. "This is terrible - I cannot find words," he said.

Vocabulary:

successor : a person who follows next in order（继任者）