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若8031单片机时钟频率为6MHz，在P1.0口接一个LED发光二极管，P1.0为低电平时点亮，运行以下程序后LED亮暗的周期为______秒，点亮的时间为______秒。 ORG 0000H LJMP BEG ORG 001BH DJNZ R7，RRT MOV R7，#200 CPL P1.0 RRT：RETI BEG：MOV TMOD，#20H MOV TH1，#6 MOV TL1，#6 SETB TR1 MOV IE，#88H SJMP $ 提示：TMOD、TCON和IE寄存器各位内容如前所示。
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Passage Two That cold January night, I was growing sick of my life in San Francisco. There I was, walking home at one in the morning after a tiring practice at the theatre. With the opening night only a week from now on, I was still learning my lines. I was having trouble dealing with my part-time job at the bank and my acting at night at the same time. As I walked, I thought seriously about giving up both acting and San Francisco. City life had become too much for me. As I walked down empty streets under tall buildings, I felt very small and cold. I began running, both to keep warm and to keep away from any possible robbers. Very few people were still out except a few sad-looking homeless people under blankets. About a block from my apartment, I heard a sound behind me. I turned quickly, half expecting to see someone with a knife or a gun. The street was empty. All I saw was a shining streetlight. Still, the noise had made me nervous, so I started to run faster. Not until I reached my apartment building and unlocked the door did I realize what the noise had been. It had been my wallet falling to the sidewalk. Suddenly I wasn’t cold or tired anymore. I ran out of the door and back to where I’d heard the noise. Although I searched the sidewalk anxiously for fifteen minutes, my wallet was nowhere to be found. Just as I was about to give up the search, I heard the garbage truck (垃圾车) pull up to the sidewalk next to me. When a voice called from the inside, "Alisa Camacho" I thought I was dreaming. How could this man know my name the door opened, and out jumped a small red-haired man with an amused look in his eye. "Is this what you’re looking for" he asked, holding up a small square shape. It was nearly 3 am by the time I got into bed. I wouldn’t get much sleep that night, but I had gotten my wallet back. I also had gotten back some enjoyment of city life. I realized that the city couldn’t be a bad place as long as people were willing to help each other. From the text, we can infer that the writer ______.
编程实现数据块传送，将片内RAM从30H开始的连续32个单元的内容传递给片内RAM从60H开始的连续32个单元。
Directions: There are 10 blanks in the following passage. For each numbered blank, there are 4 choices marked A, B, C and D. One summer day my father sent me to buy wire for our farm. At 16, I liked (76) better than driving our truck, (77) this time I was not happy. My father had told me I’d have to ask for credit at the store. Sixteen is a (78) age, when a young man wants respect, not charity. It was 1976, and the ugly (79) of racial discrimination was (80) a fact of life. I’d seen my friends ask for credit and then stand, head down, while the store owner (81) whether they were "good for it." I knew black youths just like me who were (82) like thieves by the store clerk each time they went into a grocery. My family was (83) . We paid our debts. But before harvest, cash was short. Would the store owner (84) us. At Davis’s store, Buck Davis stood behind the cash desk, talking to a farmer. I nodded (85) I passed him on my way to the hardware shelves. When I brought my purchases to the cash desk, I said carefully, "I need to put this on credit."
Passage Three Parents should stop blaming themselves because there’s not a lot they can do about it. I mean the teenager (十几岁的孩子) problem. Whatever you do or however you choose to deal with it, at certain times a wonderful, reasonable and helpful child will turn into a terrible animal. I’ve seen friends deal with it in all kinds of different ways. One strict mother insisted that her son should stand up whenever anyone entered the room, open doors and shake hands like a gentleman. I saw him last week when I called round. Sprawling himself (懒散地躺) on the sofa in full length, he made no attempt to turn off the loud TV he was watching as I walked in, and his greeting was no more than a quick glance at me. His motherwas ashamed. "I don’t know what to do with him these days," she said. "He’s forgotten all the manners we taught him." He hasn’t forgotten them. He’s just decided that he’s not going to use them. She confessed (坦白) that she would like to come up behind him and throw him down from the sofa onto the floor. Another good friend of mine let her two daughters climb all over the furniture, reach across the table, stare at me and say, "I don’t like your dress; it’s ugly. " One of the daughters has recently been driven out of school. The other has left home. "Where did we go wrong" her parents are now very sad. Probably nowhere much. At least, no more than the rest of that unfortunate parents. What is the author’s opinion about the sudden change in teenage children
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