Which of the following is not true about hydraulic systems?
a. over half of all system problems are traced directly back to the oil
b. fire-resistant fluid should be used in applications where human safety is of concern
c. hydraulic fluid must have good lubricity to prevent wear between closely fitted working parts
d. in hydraulic systems, the operating temperatures must be kept between 170°f and 180°f
e. none of the above

The answer is D

D.In hydraulic systems, the operating temperatures must be kept between 170�F and 180°F 

Explanation:

The operating temperature for hydraulic systems is 140°F and below. Anything above this temperature is too high and will reduce the useful life of hydraulic fluid.

Most often problems associated with hydraulic systems are caused by fluid contaminated with particulate matter.

answer:

explanation:

assault rifle is a rapid-fire, magazine-fed rifle designed for military use. it is a shoulder-fired weapon that allows the shooter to select between semi-automatic (requiring you pull the trigger for each shot), fully automatic (hold the trigger and the gun continuously fires) or three-shot-burst modes.