帮忙翻译几个句子
1.dinosaurs first appeared about 230 million years ago
2.the earth was very different back then-there were no mammals,there were no flowering plants,and all of the continents joined together in a giant land mass called Pangaea
3.today scientists aren't really sure how many different dinosaurs may have existed
4.there were probably many more dinosaurs,and scientists haven't yet found any bones or fossils for them
参考答案:1.恐龙出现约230万年前 2.地球很出入,没有动物,没有花卉,大陆所有的大联合要求面积Pangaea 3.现在科学家不知道恐龙存在不同 4.恐龙可能更多,科学家尚未发现这些骨骼化石