According to a report , more than a million workers will fail to take their full annul leave  this year in UK. That's to say, totally, those workers will give up 6.2 million days of vacation, with an average of five days for each worker. For their employers, they feel happy because that is equal to a potential $500 million of 'free' work, which, according to an economist will boost  the output of the economy by about two percent. The report also showed that the main reasons employees give up their remaining annul leave are due to pressures at work and their failing to appreciate that taking a break could make them more productive and, in turn, boost the economy in the long term. The research, done by price comparison website Travel Supermarket, found that more than one in four of those who will give up their remaining holidays (28 percent) will do so due to pressures at work. Bob Atkinson, travel expert for Travel Supermarket said: "As the economy is not so satisfying, it's no surprise that people are cautious to take all their leave, especially if they feel stressed and uncertainty at work." Nine percent of the 2,020 people surveyed also said they would feel guilty about taking the leave because their work would have to be taken care of by their colleagues. A further three percent said they would be concerned about how taking time off would look to their employer, while the same percentage said they did not want to miss anything interesting or beneficial at work in the time they would be away. Vicky Redwood, chief UK economist at Capital Economics, said: "Suppose that there are about 250 working days in a year, getting an extra five 'free' days of work from their employees could in theory boost the output of  the economy by about two percent. On the other hand, if workers are less productive as a result of not getting enough breaks from work, taking all the annual leave, in fact, will perhaps increase the economy." Which of the following is NOT a reason why employees don't take all their holiday leave?
They have a lot of pressures at work. They don't realize that they will be more productive after taking a break. They are busy and have no time because they have a lot of work to do. They don't think it proper to have their work taken care of by their colleagues.