<image>(2013 Autumn • Huaibei Final Exam) A motor vehicle started with 42 liters of fuel in the tank, and after driving for several hours, it refueled a certain amount at a gas station. The remaining fuel in the tank Q (liters) as a function of the driving time t (hours) is shown in the graph. Based on the graph, answer the following questions:
(1) The motor vehicle refueled after driving for _____ hours;
(2) The functional relationship between the remaining fuel Q in the tank and the driving time t before refueling is ____, and the domain of this function's independent variable t is ____;
(3) The amount of fuel refueled during the trip was ____ liters;
(4) If the distance from the gas station to the destination is 230 km and the car speed is still 40 km/h, is the fuel in the tank enough to reach the destination? Please explain your reasoning.