For convenience it is common to speak of plants as "herbs, " "shrubs, " and "trees, " but it is really no sharp distinctions among them 此题为多项选择题。请帮忙给出正确答案和分析,谢谢!
Because of the rising cost of fuel, scientists are building automobile engines who will conserve gasoline but still run smoothly 此题为多项选择题。请帮忙给出正确答案和分析,谢谢!
Anthropologists agree that our primitive ancestors who inhabited the tropics probably have natural protection against the sun 此题为多项选择题。请帮忙给出正确答案和分析,谢谢!