step_by_step3000第三册unit1答案及原文(23)

Laser Bored

Yeast Friendly / intimate

Friction Loudly but neutral

Recycling Patiently

Tapescript:

1 .... Yes, you see, it's the force of attraction between any two objects. The strength of the force depends on the mass of the objects and the distance between them. Er... the most obvious effect is the way objects on the surface of the earth are attracted towards the center of the earth...

2 .... as it comes down it goes relatively slowly 100 to 1,000 miles per hour and you can't see it, but the return stroke goes up from the earth to the cloud and it goes at over 87,000 miles per hour and that's the one you can see, you see, the one that goes back up. It's really just a very large, powerful spark. The distance in miles you are away from it is the time in seconds between it and the sound you hear...

3 .... Well, they were first discovered in 1895 and they can penetrate matter that is opaque to light. Some matter is more transparent to them than others, which means you can see inside somebody. They are actually quite dangerous and people who work with them wear special protective clothing...

4 .... ordinary light consists of electromagnetic waves of different frequencies and phase(s). This is a bundle of waves of the same frequency and phase. You can create the beams from a ruby rod or a tube of carbon dioxide that's stimulated with flashes of ordinary light. The word is an acronym for light amplification by the stimulated emission of radiation. Now, does anybody ...

5 .... they're all types of fungus. There are many different kinds of them but the best known are the ones used in cooking and brewing. When they're mixed with sugar they cause the sugar to

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