柳工939FE拖(tuō)电挖掘机(jī)的优点包括：1. 环保节能：该挖掘机(jī)采用电动机(jī)作(zuò)为动力(lì)源，与传统的内燃(rán)机(jī)挖掘机(jī)相比，无排放、无噪音、无燃(rán)油消耗，减少了对环境的污染。2. 经济(jì)实用：拖(tuō)电挖掘机(jī)使用电力(lì)作(zuò)为动力(lì)源，相比燃(rán)油价格较稳定，使用成本较低。3. 高效灵活：拖(tuō)电挖掘机(jī)采用电动机(jī)作(zuò)为动力(lì)源，转速快，启动迅速，操作(zuò)灵活，可以根据工作(zuò)需求灵活调整挖掘机(jī)的转速和力(lì)度。4. 无需加油和维护成本低：拖(tuō)电挖掘机(jī)无需加油，同时电动机(jī)的维护成本相对较低，不需要经常更换零部件。5. 能量回收：由于拖(tuō)电挖掘机(jī)采用电动机(jī)作(zuò)为动力(lì)源，在刹车或者淘汰作(zuò)业时，电动机(jī)可以将能量转化为电能，进行能量回收，提高能源利用率。总之，柳工939FE拖(tuō)电挖掘机(jī)具有环保节能、经济(jì)实用、高效灵活、无需加油和维护成本低、能量回收等(děng)优点，适用于各种挖掘、土石方、基建工程等(děng)工作(zuò)。

The advantages of LiuGong 939FE tractor excavator include: 1. environmental protection and energy saving: this excavator adopts electric motor as power source, compared with the traditional internal combustion engine excavator, there is no emission, no noise, no fuel consumption, which reduces the pollution to the environment. 2. economic and practical: the tractor excavator adopts electric power as power source, which makes the cost of using it lower compared with the price of fuel, which is more stable. 3. high efficiency and flexibility: tractor excavator adopts electric motor as power source. Electric motor as power source, fast speed, quick start, flexible operation, according to the needs of the work of the excavator can be flexibly adjusted rotational speed and strength. 4. no refueling and low maintenance costs: traction excavators do not need to refuel, while the maintenance cost of the motor is relatively low, do not need to frequently replace parts. 5. energy recovery: because the traction excavator adopts the electric motor as a power source, in the braking or elimination of operations, the electric motor can convert energy into electricity. The electric motor can convert the energy into electricity for energy recovery and improve the energy utilization rate. All in all, LiuGong 939FE tractor excavator has the advantages of environmental protection and energy saving, economic and practical, high efficiency and flexibility, no refueling and low maintenance cost, energy recovery, etc. It is suitable for all kinds of excavation, earthmoving, infrastructure projects and other work.