题目

下列细胞结构属于生物膜系统的是  A．中心体         B．核糖体           C．染色体        D．内质网 答案：D Frank was a very talkative boy. He never saw a new thing without asking a lot of questions about it. His mother was very kind and ________ . When it was proper to answer his questions, she would do so.The first time Frank saw an hourglass, he was very much ________, but he did not know what it was. His mother ________,“An hourglass is made in the shape of the figure ‘8’. The sand is put in one end, and ________ a small hole in the middle. The sand put into the glass will go through ________ an hour. ”Frank watched the little stream of sand. He was impatient, because it would not run faster. “Let me ________ it, Mother,” said he. “It is lazy, and will never get through.”“Oh yes, it will, my son ,” said his mother. “The sand moves by ________, but it moves all the time. When you look at the clock, you will find the same. ________ you are playing, the sand is running, grain by grain, and the hands of the ________ are moving, second by second. At night, the sand in the hourglass has run through twelve times. The hour hand of the clock has moved all around ________ great face. This is because they keep at work every ________. They do not stop to think how much they have to do, and ________ it will take them to do it. ”Now, Frank’s mother wanted him to learn a poem, but he said, “Mum, I ________. ” His mother said ,“Study all the time. ________ care about the time it will take. You will be able to say it very soon. ”Frank followed his mother’s ________. He studied line after line, and in one hour and a half he knew the poem perfectly.1.A.strict B.patient C.nervous D.polite2.A.pleased B.relaxed C.interested D.bored3.A.explained B.repeated C.thought D.added4.A.runs through B.runs along C.goes over D.goes across5.A.before B.for C.after D.in6.A.shake B.get C.take D.carry7.A.carefully B.quickly C.heavily D.slowly8.A.Since B.Unless C.Before D.While9.A.boy B.mother C.clock D.hourglass10.A.his B.her C.its D.their11.A.year B.month C.week D.minute12.A.how far B.how long C.how much D.how soon13.A.can B.can’t C.could D.couldn’t14.A.Often B.Never C.Always D.Sometimes15.A.rule B.steps C.advice D.decision