题干

某种昆虫靠翅膀振动发声,如果这种昆虫的翅膀在一分钟内振动了300次,则它振动的频率是____ Hz,人类____听到这种声音(选填“能”或“不能”);地震是一种严重的自然灾害,地震时产生的____(选填“超声波”或“次声波”)对人的器官功能的破坏性很大,使人产生恶心、晕眩、旋转感等症状,严重的会造成内脏出血破裂,危及生命.它的破坏性大,并且它的频率____ 20Hz(选填“高于”、“等于”或“低于”).
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5Hz,不能,次声波,低于

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    “Cleverness is a gift while kindness is a choice. Gifts are easy – they're given after all. Choices can be hard.” –– Jeff Bezos.

    I got the idea to start Amazon 16 years ago. I came across the fact that the Internet usage was growing at 2,300 percent per year. I'd never seen or heard of anything that grew that fast, and the idea of building an online bookstore with millions of titles was very exciting to me. I had just turned 30 years old, and I'd been married for a year. I told my wife MacKenzie that I wanted to quit my job and go to do this crazy thing that probably wouldn't work since most start-ups don't, and I wasn't sure what to expect. MacKenzie told me I should go for it. As a young boy, I'd been a garage inventor. I'd always wanted to be an inventor, and she wanted me to follow my passion.

    I was working at a financial firm in New York City with a bunch of very smart people, and I had a brilliant boss that I much admired. I went to my boss and told him I wanted to start a company selling books on the Internet. He took me on a long walk in Central Park, listened carefully to me, and finally said, “That sounds like a really good idea, but it would be an even better idea for someone who didn't already have a good job.” That logic made some sense to me, and he convinced me to think about it for 48 hours before making a final decision. Seen in that light, it really was a difficult choice, but ultimately, I decided I had to give it a shot. I didn't think I'd regret trying and failing. And I suspected I would always be haunted by a decision to not try at all.

    After much consideration, I took the less safe path to follow my passion, and I'm proud of that choice. For all of us, in the end, we are our choices.