题目

如图是某生物的精细胞，根据图中的染色体类型和数目，判断其至少来自几个初级精母细胞？（）      A．1    B．2    C． 3    D． 4 答案：BThe sun is shining when I get on No. 151 bus. We passengers sit jammed together in heavy clothes. No one speaks. That’s one of the unwritten rules of Chicago commuting. Although we see the same faces every day, we prefer to hide behind our newspapers. The phenomenon is striking: people who sit so close together are using those thin sheets of newsprint to keep their distance.As the bus approaches the Magnificent Mile, a voice suddenly rings out: “Attention! Attention!” Papers rattle (发出细小声). Necks crane (伸长). “This is your driver speaking.”We look at the back of the driver’s head. His voice has authority.“All of you put your papers down.”The papers come down, an inch at a time. The driver waits. The papers are folded and placed on our laps.“Now, turn and face the person next to you. Go ahead.”Amazingly, we all do it. Still, no one smiles.I face an older woman, her head wrapped tightly in a red scarf. I see her nearly every day. Our eyes meet. We wait, unblinking, for the next order from the driver.“Now, repeat after me…” It is a command, delivered in the tones of a drill sergeant (教官). “Good morning, neighbor!”Our voices are weak and timid. For many of us, these are the first words we have spoken today. But we say them at the same time, like schoolchildren, to the strangers beside us.We smile and can’t help it. We have said it; the barrier has been broken. Good morning, neighbor. It is not so hard after all. Some of us repeat it. Others shake hands. Many laugh.The bus driver says nothing more. He doesn’t need to. Not a single newspaper goes back up. I hear laughter, a warm sound I have never heard before on bus No. 151. This day is starting off better than most.1.On hearing the sudden utterance of “Attention!”, the passengers ___________.A. stopped reading and put down their newspapers immediatelyB. looked up from the newspapers to see who was speakingC. sat still without responseD. were frightened2.The underlined word “commuting” in Paragraph 1 most probably means ___________.A. daily traveling between home and workB. long-distance rideC. communication technologyD. behavior patterns3.Which of the following is true according to the passage?A. The passengers on the crowded bus were so absorbed in reading their newspapers that no one spoke.B. The passengers were physically close together but mentally they kept each other at a terrible distance.C. The passengers didn’t follow the driver’s instruction at first.D. When the bus driver said nothing more, the passengers picked up and read their newspapers again.4.What would be the best title for the text?A. The Warmth of CommunicationB. The Exchange of InformationC. The Power of ObservationD. The Attitude to Loneliness