新托福阅读资料:蜂鸟
蜂鸟是一种非常美丽而且奇特的小生物,下面的新托福考试阅读特训资料中我们就来看看与蜂鸟相关的信息。 Most birds flap their wings up and down, but hummingbirds move their wings in a figure-eight pattern. With each flap they twist their wings one-hundred-eighty degrees so that they create a downward thrust on both the forward and backward strokes. If each loop of the wings is of the same strength, they hover. They can go forward, backwards, or sideways by tilting their wings in the direction they want to go. Kind of like a helicopter.Exactly. In order to hover, hummingbirds have to be really ... [ 查看全文 ]新托福阅读资料:蜂鸟的相关文章
新托福阅读练习资料:Fatherless Honeybees
蜜蜂的社会有哪些特殊之处?今天的新托福考试阅读练习资料中我们就要了解这方面的信息。 How male honeybees can be without fathers? The reason lies in what’s called a haploidiploid system of sex determination. Approximately one-fifth of t...[ 查看全文 ]