For an engine to operate correctly, air must flow into and out of the engine without restriction.

为了使得发动机正常运转，空气必须无阻碍地进出发动机。

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Conclusion the contamination of air in the operating room is severe, the restriction of the activity and the number of staff in the operating room can reduce the precipitating bacterial density.

结论手术过程中洁净手术室空气细菌污染严重，限制手术人员活动和人数可降低沉降菌密度。

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Night Bombing. City attacks (Manpower only) for non-game designated air units. No restriction on night naval attacks.

禁止夜间轰炸。不是原生的夜间战机参与夜间轰炸只能炸人力资源。不限制夜间对海攻击。

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The recent food scares have also led to tightening food safety regulations, limiting what can and can't be sold on and off the farm, and how producers have to package their food -- a restriction that is especially challenging at an open-air farmers market, Fahy said.

CNN: 'Farm fresh' movement a growing food trend

An additional restriction is that vessels must have less than a 190-foot air draft.

FORBES: The Port of New York and New Jersey, a Critical Hub of Global Commerce

Air Wales had hit the headlines last year by appealing for cabin crew under 5ft 3 inches - a height restriction it insists on because of tight space on the aircraft.

BBC: Take-off for budget City flights