摘要： Example: The mirror had a convex surface. 镜子有一个凸面。 The convex shape of the lens allows it to focus light. 透镜的凸起形状使其能够聚焦光线。 阅读全文

摘要： Example: All rights reserved. No part of this book may be reproduced, stored in a retrieval system 阅读全文