题目

1952年“噬菌体小组”的赫尔希和蔡斯研究了噬菌体的蛋白质和DNA在侵染过程中的功能，请回答下列有关问题： （1）他们指出“噬菌体在分子生物学的地位就相当于氢原子在玻尔量子力学模型中的地位一样”。这句话指出了噬菌体作实验材料在结构和成分上具有____________________________的特点。 （2）通过_________________________________________的方法分别获得被32P和35S标记的噬菌体，用标记的噬菌体侵染细菌，从而追踪在侵染过程中____________________变化。 （3）侵Most sharks are dangerous. The largest kind of sharks—the whale shark—has small teeth and is quite harmless to people. However, blue sharks, tiger sharks, white sharks and hammerheads are enemies of man.Man-eaters are always a danger to swimmers in shark waters. Sometimes, though, men have used strange methods when they’re suddenly faced with a shark.During world War Ⅱ, soldiers and sailors whose boats or planes were destroyed drifted(漂流) helplessly on the ocean in small rafts(筏子). While waiting to be saved, the men had to struggle to stay alive and were often attacked by sharks. In some cases, they had few weapons to protect themselves with. They found that just splashing(溅水) water seemed to help keep the sharks away.One sailor was swimming for his life in the Atlantic Ocean after his boat had been blown up. He saw a shark swimming towards him. He hit the shark with his bare fist, and that drove it off.Once, in Australia, a fisherman was fishing after sunset. He hooked a big fish and drew it towards the shore. His line broke when the fish was only a few yards from the shore. The fisherman waded(涉水) into the water to try to catch it with his hands. In the dim light, it looked like the kind of fish that could be dealt with without danger.He put his arms around the fish and wrestled with it. Dragging it to the beach turned out to be harder than he had expected, but at last he pulled it in. When he turned a light on it, he was amazed. He had caught a shark. It was small for a shark, but it was the man-eating type and was about as long as a tall man.In a word, the best way to deal with sharks is to keep far away from them.60. The shark that is least dangerous to man is the ________.A. white shark      B. whale shark   C. tiger shark     D. hammerhead shark61. This story tells you that sharks are usually ________.A. friendly         B. small         C. afraid of people     D. dangerous62. After the Australian fisherman found he had caught a shark, he was _________.A. surprised      B. frightened      C. unhappy      D. angry63. This story tells you that the best way to handle sharks is to ________.A. hit them with your fist                 B. keep far away from themC. splash water                         D. wrestle with them64. The passage mainly tells us something  ________.A. about fishing sharks                  B. about sharks C. how to eat  sharks                   D. that sharks are man’s enemies