例题汽车停车场有10辆汽车,第一辆汽车出发后,每隔4分,有一辆汽车开出.在第一辆汽车开出2分后,有一辆汽车进站,以后每隔6分即有一辆汽车回站.回站的汽车,在原有的10辆汽车之后又依次每隔4分开出一辆.问从第一辆汽车开出后,经过多少时间,停车场就没有汽车了. Example: There are 10 cars in the car park. After the first car starts, every 4 minutes, a car is opened. After 2 minutes from the first car, a car enters the station and every 6 minutes thereafter. There is a car back to the station. The cars that return to the station are separated from each other by four cars in turn after the original 10 cars. After asking how much time has passed since the first car was opened, the parking lot has no cars.