单项选择题
The author states that birds left the tropics because （）
A．there was not enough food there in the winter B．there were too many birds C．there were too many glaciers D．there was too much daylight
单项选择题 According to one theory, when the glaciers disappeared, birds（）
单项选择题 This passage supports the belief that（）
单项选择题 The underlined part "the law is loaded against him" in the second paragraph is most likely to mean （）
