2．下列有关细胞器的叙述，正确的是　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 (　　 )

　 　　 A．原核生物的细胞结构中无线粒体，只能通过无氧呼吸获取能量

　 　　 B．在生物细胞有丝分裂的后期，染色体向两极移动与中心粒发出的星射线形成的纺锤体牵引有关

　 　　 C．抗体在核糖体合成后，依次进入内质网和高尔基体加工

　 　　 D．叶绿体普遍存在于绿色植物体细胞中，可通过光合作用制造有机物

1．成熟的神经细胞在兴奋时，下列几种酶中活跃的是　　　　　　　　　　　　　　　　　　　　　　　　　 (　　 )

　 　　 A．RNA聚合酶　　　　　　　　　　 　 B．DNA解旋酶

　 　　 C．蛋白酶、脂肪酶 　　　　　　　　　　　　　　　 D．与ATP和ADP相互转化有关的酶

50.It’s ______ to borrow money from your mother to settle your debt to your uncle. That’s just robbing Peter to pay Paul.

A.ridiculous　　　　　 B. strange　　　　　 C. stubborn　　　 D. splendid

49.Everything works out well. ____, we are sure that the experiment will be completed on time.

A.Therefore　　　　　　 B. While　　　　　 C. However　　　　　 D. Otherwise

48.Although my grandfather is in his eighties, he is still as ______ as a young man and hates sitting around doing

nothing all day.

A. enthusiastic　　　　　 B. automatic　　　 C. energetic　　　　　 D. innocent

47.He was robbed last night, but 　　　　he didn’t have much on him then.

A.fortunately　　　　　　　 B.eventually　　　　　　　 C.certainly　　　　　　　　 D.surprisingly

46.Letterboxes are much more ____ in the UK than in the US, where most people have a mailbox instead.

A. common　　　　　 B. normal　　　　 C. ordinary　　　　 D. usual

45.After I arrived at her house, she showed me into ____________.

A. a room cosy or little　　　 B. a little cosy room　　 C. a cosy little room　　 D. cosy little a room

44.The workers are so _____ to the noise of the machine that they don’t even notice it during their work.

A. accustomed　　 B. subjective　　　 C. familiar　　　　　　 D. associated

43. It is not　　 for me to return all the books to the library now because I still need them.

A. mature　　　　　　　　　 B. convenient　　　　　　 C. available　　　　　　　　 D. tight