Passage 4Time zonesWhen it is noon in Rio de Janeiro, it is midnight in Tokyo. This is because we divide the earth into different time zones. Within each zone, people set their clock for the same time. If someone travels by plane between two zones, he or she will adjust his/her clock to the one used in the new zone.There are 24 time zones, separated by one-hour intervals, with each 15 degrees longitude. The zones were measured according to the Greenwich Mean Time, used as the starting time zone, which measured hours before and after GMT.Governments can change their country’s time zone. Thus, for convenience, entire countries tend to adjust to the same local time rather than adjusting exactly to the zones. For example, China could be divided into several time zones, but instead, the whole country uses the same time. Some areas, such as parts of India, Iran, and Australia, use non-standard half-hour deviations.On the opposite side of the earth to the starting time zone, a date-line runs mainly through the Pacific Ocean, avoiding the mainland. The locations to the west are 24 hours ahead of the east of the line. This means that if we travel through it in the east, we will lose one day, while we will gain one day to the west.题目： How many hours is the difference between to neighbor time zones?