Aircraft are at their most vulnerable to bird strikes during take off and landing: over 60% of all bird strikes occur below 100 feet, less than 8% above 3, 000 feet.
飞机在起飞和降落是最易遭受撞鸟事件的:超过60%的撞鸟事件发生在低于100英尺,在3000英尺以上不到8%。
He looked at 43 previous studies that had carefully screened 3, 000 bird species for malaria in different locations over the past 70 years.
他查阅了43份此前的研究——在过去70年,为研究不同地区的疟疾,仔细拍摄了3000种鸟类。
Its alert system was revised after bird flu in Asia began to spread in 2004, and Monday was the first time it was raised above Phase 3.
它的警报系统在2004年禽流感开始在亚洲蔓延后进行了修订,星期一是它的警戒系统第一次提升到第3级别。
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