单选题At ground level, nitrous oxides are bad enough, but when up high, atmospherically they bond with free ions to create dangerous smog particles.A but when up high, atmospherically theyB however, it is in the upper atmosphere in which it mayC but in the u

In which circumstance are multiple copies of the same unicast frame. likely to be transmitted in the Ezonexam Switched LAN?

A. During high traffic periods

B. In an improperly implemented redundant topology

C. After broken links are re-established

D. When upper-layer protocols require high reliability

E. When a dual ring topology is in use

F. None of the above

A. after broken links are re-established

B. in an improperly implemented redundant topology

C. when upper-layer protocols require high reliability

D. during high traffic periods

E. when a dual ring topology is in use

The correct procedure for giving an auxiliary boiler a bottom blow, is to begin .

A.when the boiler has been secured long enough for most solids to settle

B.when the boiler has been cooled to ambient temperature

C.only after raising the water level to within 0.5 inch of the high water cutout only

D.after bypassing the low pressure

When you are making a high potential test on a piece of repaired electrical machinery, a rise in leakage current indicates _______.

A.good insulation

B.bad insulation

C.high insulation power factor

D.a high slot discharge factor

Which statement about inert gas pressures in a cargo tank is TRUE ________．

A.The pressures of the inert gas in the tank may create excessive pressure at the pump while discharging

B.Gas pressures should be maintained at the highest permissible level throughout the discharging process

C.High gas pressures may cause pyrophoric oxidation in the tank

D.High gas pressures may cause loss of suction when stripping

In order to help the new employees to maintain a high level of motivation and build up confidence ，a well-planed program is necessary.()