这张邮票的 价目 是五美元.This stamp catalog ( ue ) s at five dollars.你是想了解某一种珍稀邮票还是想了解珍稀邮票的整体概念？Do you want to know about a particular rare stamp or rare stamps in general?这张旧邮票的背面没黏性了, 我得用胶把它粘在信封上.This old stamp isn't sticky ...
The electron microscope uses a beam of electrons to produce images at high magnifications.电子显微镜利用电子束形成高倍影像。The structure of molecules can be seen under an electron microscope.分子的结构可在电子显微镜下观察到.The electron microscope uses...