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The din of helicopters and private jets is omnipresent .

直升机和私人飞机的噪声无处不在。

New helmets are specially adapted for helicopters .

新式头盔专为直升机驾驶员配置。

They flee from motorboats and helicopters .

他们总是远远地避开摩托艇和直升机。

Both have helicopters and water cannon .

双方都备有直升机和高压水枪。

Helicopters perform poorly in hot weather and at high altitude .

直升机在天气炎热和海拔较高时表现不佳。