在正方形ABCD中，AB=4沿对角线AC将正方形ABCD折成一个直二面角$B-AC-D$，则点B到直线CD的距离为（     ）

展开想象续写句子。

一幕幕惊心动魄的战斗场面由她导演出来,一支支悦耳的乐曲由她指挥而生，                                               。

    Do you need useful and interesting books? Here we've got plenty for you.

Successful Fishermen

    Fishing is a healthy hobby. You can enjoy fresh air when you go fishing in the countryside. This book will teach you how to choose fishing places and how to make good fishing rods easily. Many kinds of fishing skills are shown in the book. Read it and you will become a more successful fisherman.

Best Learners

    This book can give you the answers to the questions most often asked by parents, teachers and students themselves. Read this book and learn:

* What the three difficulties in study are and what to do with them.

* What to do if you are not interested in a subject you are studying.

* Twenty-six simple exercises to help you study easily and fast.

You will get more from this book. For younger students, you can buy Learn in

Study for Beginners. It is easier to understand.

How to Keep Pets

A pet can be our best friend. Do you have pets in your house? Are they in good shape? This book not only offers you many colorful pictures of lovely pets, but also provides you with the knowledge about:

* How to choose right pets for yourself.

* How to build houses or nests for your pets.

* How to feed the pets and how to keep them clean.

Buy this book and you will learn more.

We have many other books on sale. For more information enter www. knowbetter. com. If you buy two or more books at a time, you'll get 10% off.

    Hello, everyone．Nice to meet you．It is my1day （天） in the school．My first name is Jenny．My family2is Green．I'm 3Class Two．My phone4 is 886-3068．There are5people （人） in my family, my parents, my two brothers and I．My brothers and I are6．We are in the same （相同的） school．Look, this is my good friend7name is Sally．She is8English girl．She is in Class9, too．10are in the classroom．We are talking happily （快乐交谈）．