柳工(gōng)939FE拖电挖掘机(jī)的(dí)优点包括：1. 环保节能：该挖掘机(jī)采用电动(dòng)机(jī)作(zuò)为动(dòng)力源，与传统的(dí)内燃机(jī)挖掘机(jī)相比，无排放、无噪音、无燃油消耗，减少了对环境的(dí)污染。2. 经济实用：拖电挖掘机(jī)使用电力作(zuò)为动(dòng)力源，相比燃油价格较稳定，使用成本(běn)较低。3. 高效灵活：拖电挖掘机(jī)采用电动(dòng)机(jī)作(zuò)为动(dòng)力源，转速(sù)快，启动(dòng)迅速(sù)，操作(zuò)灵活，可以根据工(gōng)作(zuò)需求灵活调整挖掘机(jī)的(dí)转速(sù)和力度。4. 无需加油和维护成本(běn)低：拖电挖掘机(jī)无需加油，同时电动(dòng)机(jī)的(dí)维护成本(běn)相对较低，不需要经常更换零部件。5. 能量回收：由于拖电挖掘机(jī)采用电动(dòng)机(jī)作(zuò)为动(dòng)力源，在(zài)刹车或者淘汰作(zuò)业时，电动(dòng)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(gōng)939FE拖电挖掘机(jī)具有环保节能、经济实用、高效灵活、无需加油和维护成本(běn)低、能量回收等优点，适用于各种挖掘、土石方、基建工(gōng)程等工(gōng)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.