单选题 The most complex problem that happens in the control system of an air conditioning plant is under weather condition.

单选题 The opening of the humidifier ’s valve of air-conditioner should be when the outdoor temperature is raised to above 5-8 °C in the winter.

单选题 The capacity of many air conditioning plants is such that under tropical conditions nearly all control valves move to the position.

单选题 When starting air-conditioner in the winter, we should open_______

①valve of steam heater ;②valve of humidifier ;③fan

单选题 Which of the following terms represents the process of increasing the relative humidity of a space by adding water vapor or steam?

单选题 In addition to normal mechanical attentions, such as is necessary.

①lubrication of bearings ;
②adjustment and lubrication of fan belts ;
③cleaning of motors ;
④careful greasing of linkages of automatic controls

单选题 To add refrigerant to the high side of an air conditioning system, you should introduce the refrigerant through the

单选题 On older ships, temperature maintenance can be made easier by increasing the of recirculated to fresh air.