阅读理解。 The guarantee on this water heater is in effect only when the heater is installed and operated in accordance with these instructions. Read these instructions thoroughly before starting. Location Select a location accessible to water lines and power supply. Do not locate the heater where water lines could be subjected to (受……影响) freezing temperature. It is recommended that the heater be located near the center of greatest hot water usage to prevent heat loss through the pipes. Electrical Connections Before any electrical connections are made, be sure that heater is full of water and that the valve(阀 门) in the cold water supply line is open. Operation When the switch is closed, the operation of this electric water heater is automatic. The thermostats are preset to the 'HOT' setting to provide a water temperature of approximately 120F to reduce the risk of being burnt. Maintenance Shut off the electric power whenever the water supply is turned off. Shut off the electric power, water supply and drain (排空) the heater completely to prevent freezing whenever the building is left unoccupied during the cold weather months. Service The trip-free devices on this heater will cut off all power if temperature of water is above 190F. If there is no hot water after a reasonable period of time, check the main fuse(保险丝) box. In the event that the fuses have not blown, call a serviceman. 1. The location of the water heater shall_____. A. be close to water lines and power supply B. be subjected to low temperature C. be in the centre of the house D. have a long distance to hot water usage 2. Before any connection of power, make sure that one thing you have to do is ____. A. to have the heater in the water B. to open the cold water inlet valve C. to shut off the thermostats D. to replace wiring diagram 3. What will happen to the heater when the temperature of water is above 190F? A. It will cause damage. B. It will blow the fuse. C. It will produce cold water. D. It will break off automatically. 4. According to the passage, we know that ____. A. the water heater works after it's installed B. the water heater works on condition that it is properly installed and operated C. to reduce the risk of being burnt, the water heater should be preset at exactly 120F D. when there is no hot water after a reasonable period of time, call a serviceman at once .