题目

从DNA分子的复制过程可以看出，DNA分子复制需要      、      、      和酶等条件。DNA分子的       结构能够为复制DNA提供精确的模板，以            的原则保证了复制的精确进行，DNA分子的这种复制方式称为              。 答案：(1)模板、原料（四种脱氧核苷酸）、能量（ATP），双螺旋，碱基互补配对，半保留复制。Martin is an American boy. He is eight years old. His parents      five years ago and he is now living with his grandmother in New York. One morning, Jimmy, one of his classmates, came to his home with an exercises book in his hand. Jimmy lives in a house not far from Martin's. They often go to school together. "Would you help me with this maths problem?" Jimmy said as soon as he came into the room. "It's too hard for me and I can't work it out." "Let me try, " Martin said. "I          it isn't too hard for me. " Martin tried his best but he couldn’t work it out,         . "If we had a small computer,  all the problems would be         for us to do. " Jimmy said. "A small computer. . . , " Martin thought for a minute,  then he said, "I've got an idea. We can         one in a shop. " "A computer is very          , and we don’t have enough money. " "That's OK," said Martin. "We can ask the new president        some money. He said he would help anyone in trouble. I' m sure he will help us. He is very rich, you know." So they decided to write a letter to the new president. Soon the letter was finished and they hurried to the post office. In front of the post office stood a small box. They         the letter into the box carefully and went home happily. The next morning ,they        he post office on their way to school. They found,__­­­­­______,  the box was not a post box but trash-box(果皮箱).小题1:A．havediedB．haddiedC．diedD．havebeendeath小题2:A．sureB．thinkC．hopeD．wish小题3:A．neitherB．eitherC．tooD．also小题4:A．easyenoughB．enougheasyC．difficultenoughD．enoughdifficult小题5:A．borrowB．lendC．bringD．buy小题6:A．expensiveB．cheapC．importantD．useful小题7:A．toB．forC．aboutD．on小题8:A．placeB．takeC．droppedD．bring小题9:A．passedB．pastC．pastedD．passing小题10:A．withtheirsurpriseB．intheirsurpriseC．totheirsurpriseD．oftheirsurprise