The author of the letter insisted that the only way to reduce the number of car accidents caused by teenage drivers is to launch an mandatory program payed by high school. By examining the explicit and implicit assumptions, we can draw a conclusion that some of these assumptions are not reliable. First, it is assumed that due to the large number of teenage driver car accidents in the past two years in Centerville, we should improve teenagers driving skill by asking them to go to a mandatory driving class in school. However, two other possibilities that could lead to the same result are omitted. One possibility is that these teenage drivers who involved in the car accidents might have attained driving class before and have had a driving license. If it is true, sponsoring mandatory driving program cannot efficiently reduce the number of teenage driver car accidents. The other possibility is that the number of car accidents teenage drivers involved do not suggest that the driving skill of teenagers is not qualified. Advanced driving skill with insufficient traffic regulation for teenage drivers may also cause car accidents. Second, the author stated that because many parents are too busy to teach their children to drive, therefore, some other instruction is necessary to make sure teenagers are safe drivers. This inference is based on an assumption that all teenagers must be drivers. it is not true because teenager can choose many other modes of transport such as subway, bicycle, bus etc. In China, few teenagers drive themselves before graduating from university. Third, parents do not have enough budget to pay for driving instruction fee does not mean the fee should be afforded by school. Teenagers are very important for country’s future development. Therefore, government should take responsible of taking care of teenagers’ safety. There are many sources where government can raise the driving induction fund.