At 9:30 p.m. yesterday, I was sitting in my chair, listening to a strange sound. It made me _________.

This was the third time I heard the _________. I didn’t know who or what made the sound. It sounded like someone was knocking at my _________, but I lived on the ninth floor!

I was too scared to open my eyes _________ the sound stopped. I thought about asking for help, but I was sure people would _________ me. “There can’t be a thief out there, ”they’d say.

“There it is again!” I shouted. My mom came into my room and _________ me what was going on. Then she heard the strange noise, too. She went into the bathroom. I wanted to stop my mom because I was afraid that _________ would happen to her. But she _________ laughing. “It’s OK, dear. It’s just a strong wind making your curtain (窗帘) shake and knock the window.”

I was very surprised. _________ then, I’ve started thinking more calmly. If such things happen again, I will do like __________ my mom did and find out the truth.

The Great Sphinx of Giza.

Most scientists agree the Great Sphinx of Giza(吉萨狮身人面像) was built around 2,500 B.C. But John Anthony West says that it's much older. If he's right,“everything anybody has learned about ancient civilizations(文明) would have to be completely revised. ” he told a magazine.

West, a writer and film­maker, first got interested in ancient history after studying the work of a French researcher. The researcher said Egyptian civilization could have developed as early as 30,000 years ago, rather than 4,500 years ago, as most experts believe.

West joined a scientist to do research together.Their research suggested that the Sphinx had been worn down(磨损) over the years by water, rather than by sand and wind.

Wait a minute? Water? How could that be? The Sphinx is in the Sahara Desert, which has been dry for 12, 000 years! However, before that time, it was very green. If it's true that water wore down the Sphinx, West thinks that it must have been built centuries earlier.

Whether West is right or wrong, it's important to challenge accepted ideas. That's how science progresses.

West gave some advice for kids: If you are interested in a topic, read everything you can on it. Do your own research. Don’t always believe everything your teachers tell you. Ask lots of questions, and find your own answers.

You must think a computer is the best thing in the world, right? You must think it works at a super speed and can do everything? Well, it’s not! In fact, the brain is much more powerful than any super computer! Think about when a glass is just about to fall off the table. Your brain controls everything that you need to do to save that glass from falling. First, your eyes check out what’s going on, then tell your brain, and your brain decides how quickly you need to react (反应), and then your muscles (肌肉) go into action. That is just from your brain. No computer could never come close to that !

The brain weighs just 3 pounds, but it controls everything you do from thinking, learning, feeling even breathing and your heart beating. Even though the brain is just 2% of your body weight, it uses around 20% of all your energy in your body. That is a lot for such a small organ (器官). There are about 100 billion tiny, tiny little cells (细胞) in your brain. There are so many that it would take you over 3,000 years to count them all!

Your brain stops growing when you’re 18, but it actually keeps on developing and learning new things. So your parents are really super smart! You won’t be able to fool them! Believe it or not, your brain NEVER stops working. Even during sleeping, the brain works for long-term memory establishment (建立). It is realized that the brain is the second organ in the body as the heart that never stops during human lives.