DoubleEagleinthefirsttransatlanticballoon,wasgreetedbyavidcrowdsinFrance.

Bats fly, rather than glide, and thus are the only mammals capable of true flight.

The megaphone(microphone) makes the voice sound louder because it points sound waves in one direction and keeps them from spreading out in all directions.

Eyespots, the most rudimentary eyes, are found in protozoan原生动物 flagellates 鞭毛虫 , flatworms 扁形虫 , and segmented worms片段 蠕虫 .

Despite the proliferation of other faster modes of transportation, the railroads remain the largest carriers of intercity freight in the United States.