【单选题】Generally, in order to be preserved in the fossil record, organisms must possess hard body parts such as shells or bones. Soft, fleshy structures are quickly destroyed by predators pr decayed by bacte...
【简答题】English is now the international language for airline pilots, scientists, medical experts, businessmen and many others. Consequently, more and more people are learning it.
【单选题】Food and Cancer Medical Experts have suspected for many years that there is a strong link between what a person eats and cancer. They say a new study provides the first evidence that vitamins could re...