【简答题】We learned that fossil fuels were formed before and during the time of the dinosaurs(恐龙). We are using up the fuels. We can save fossil fuels by protecting and finding ways to use energy from “endless...
【单选题】根据以下材料,回答题 Black Holes (1) Black holes can be best described as a sort of vacuum, sucking up everything in space. Scientists have discovered that black holes come from an explosion of huge stars. Star...