A：存在于病毒内
B：动物细胞比绿色植物细胞的线粒体数量多
C：细胞内需能的部位线粒体比较集中
D：生长和代谢活动旺盛的细胞线粒体数量多
-- What will a science museum be like if you are asked to build one? -- I hope it will like a book.
—Why don't you ask your brother __________ help?
