题目

阅读下面短文，根据其内容写一篇60词左右的内容概要。 Scientists have announcedthat they have cloned the first human embryo. This has caused much debate roundthe world. On the one hand, some scientists point out that if you clone anembryo, you can produce valuable human tissues—such as bone or lung tissue—thatcould be used to save human lives. On the other hand, many people, includingsome scientists, disagree and are afraid that, if mankind toys with nature inthis way, we may be on our way to producing a real-life Frankenstein's monster. Cloning is producing anexact co如图，⊙O的直径AB=6cm，P是AB延长线上的一点，过P点作⊙O的切线，切点为C，连接AC，若PC=，∠CPA=    ．