[originaltext] Six hundred extra armed officers are to be trained and patrol

Six hundred extra armed officers are to be trained and patrols will be more than doubled to help counter the threat of a terrorist attack in London, the Metropolitan Police has announced. It will bring the total number of armed officers in the capital to 2,800.
    Met Commissioner Sir Bernard Hogan-Howe said: "It will be an expensive option, but is vital to keeping us safe." It comes after Scotland Yard reassessed its ability to respond to armed attacks after last year’s Paris terror attacks. The plan to increase the number of armed officers-which is already under way-will more than double the Met’s number of armed response vehicles. The increase in armed officers would not change the fundamental principle that police in the UK are not routinely armed, with about 92% of the Met officers still unarmed, he added.
Questions 3 and 4 are based on the news report you have just heard.
3. Why is London going to increase armed officers?
4. What is the fundamental principle for the UK police?