對于晶體的x射線衍射,主極大的位置由下列那個公式確定[ ]

                          We ail know that it is possible for ordinary people to make their homes on the equator (赤道) ,although often they may feel uncomfortably hot there. Millions do it. But as for the North Pole (北極)—we know that it is not only a dangerously cold place, but that people like you and I would find it quite impossible to live there. At the present time only the scientists and explorers can do so, and they use special equipment. (76)Men have been travelling across and around the equator on wheels, on their feet or in ships for thousands of years; but only a few men, with great difficulty and in very recent time. have ever crossed the ice to the North Pole. So it may surprise you to learn that, when traveling by air, it is really safer to fly over the North Pole than over the equator. Of course, it is not true about landings in the polar region, but the weather, if we are flying at a height of 5,000 meters above the Pole is a delight. At 4,000 meters and move above the earth you can always be sure that you will not see a cloud in the sky as far as your eyes can reach. In the tropics (熱帶), on the other hand, you are not certain to keep clear of bad weather even at such heights as 18,000 or 20,000 meters.Nowadays most people decide quite【61】what kind of work they would do. When I was at school, we had to choose【62】when we were fifteen. I chose scientific subjects. "【63】, scientists will earn a lot of money," my parents said.【64】I tried to learn physics and chemistry, but in the【65】I decided that I【66】a scientist. It was a long time【67】I told my parents that I wasn't happy at school. " I didn't think you were," said my mother. "【68】," said my father. "Well, the best thing to do now is to look for a job. "下列情況中應澆灑黏層瀝青的是()。。


                          One summer night, on my way home from work I decided to see a movie. I knew the theatre would be air-conditioned and I couldn't face my【21】apartment. Sitting in the theatre I had to look through the【22】between the two tall heads in front of me. I had to keep changing the angle every time she leaned over to talk to him,【23】he leaned over to kiss her. Why do Americans display such affection in public places? I thought the movie would be good for my English, but【24】it turned out, it was an Italian movie.【25】about an hour, I decided to give up the movie and【26】on my popcorn(爆玉米花). I've never understood why they give popcorn! It tasted pretty good,【27】. After a while I heard【28】more of the romantic-sounding Italians. I just heard the sound of the popcorn crunching (咀嚼) between my teeth. My thought started to【29】. I remembered when I was in South Korea (韓國), I【30】to watch Kojak on TV frequently. He spoke perfect Korean—I was really amazed. He seemed like a good friend to me,【31】I saw him again in New York speaking perfect English instead of perfect Korean. He didn't even have a Korean accent and I【32】like I had been betrayed. When our family moved to the United States six years ago, none of us spoke any English.【33】we had begun to learn a few words, my mother suggested that we all should speak English at home. Everyone agreed, but our house became very【34】and we all seemed to avoid each other. We sat at the dinner table in silence, preferring that to speaking in a difficult language. Mother tried to say something in English but it【35】out all wrong and we all burst into laughter and decided to forget it! We've been speaking Korean at home ever since.The entire family is ______ in scientific research.Persistence method will work well ______。