London taxi drivers know the capital like the back of their hands. No matter how small or indistinct the street is, (1)_____________________. The reason London taxi drivers are so efficient is that they all have gone through a very tough training period to get special taxi driving license. During this period, which can take two to four years, the would-be taxi driver has to learn the most direct route to every single road and to every important building in London. To achieve this, (2)___________________. Learner taxi drivers are tested several times during the training period by government officers. The exams are terrible experience. The officers ask you "How do you get from Birmingham palace to the Tower of London?" and you have to take them there in the direct line. When you get to the tower, they won't say "well done". They will quickly move on to the next question. After five or six questions, they will just say "See you in two months' time." and then you know the exam is over. (3)_____________________. Therefore, many of them keep their previous jobs until they have obtained the license. The training can cost quite a lot, because learners have to pay for their own expenses on the tests and the medical exam.