题干

下列技术依据DNA分子杂交原理的是( )

①用DNA分子探针诊断疾病

②快速灵敏地检测饮用水中病毒的含量

③B淋巴细胞与骨髓瘤细胞杂交

④目的基因与运载体结合形成重组DNA分子.

A:②③

B:①②

C:②④

D:①④

上一题 下一题 0.0难度 选择题 更新时间:2019-06-10 12:08:57

答案(点此获取答案解析)

B

同类题1

根据短文内容,选择正确答案。
    Maybe you know floods, earthquakes, sandstorms and so on. But have you heard of typhoons?
    Typhoons are some of the worst storms, usually around the Pacific Ocean and the South China Sea. Most happen in July, August and September.
    How does a typhoon happen? When lots of sea water gets hot in the summer sun, it evaporates (蒸发)into the air. This makes the air hotter. When the air gets warm enough, it starts to move higher up into sky. Then cooler air around it rushes in. It fills the space that is left. After the air gets warmer, it starts to move quickly, making wind. The wind goes in circles(圆圈)and it keeps moving higher in the sky. The warmer the air gets, the quicker the wind moves. And when the wind moves faster than 30 metres a second, a typhoon begins.
    A typhoon has two parts, one is called the “eye”. In the eye, the wind does not move so fast. The other part is the wall of clouds around the eye. Here are the strongest winds and hardest rains.
    Typhoons are very dangerous. In November this year, Typhoon Haiyan killed 5500 people in Philippines. More people are missing.
    What to do when a typhoon hits?
    Stay inside. Close all the windows and stay away from them.
    Try to bring all of your things inside. Strong winds could even blow away your bikes!
    Listen to the radio or TV for important information.
    If you're told to go to a safer place, do it right now.

同类题3

   “Everything happens for the best,” my mother said whenever things weren't going my way. “Don't worry, one day your luck will change.” Mother was right, as I discovered after I had finished my college education. I had decided to find a job in radio. One day, I wanted to host(主持) a sports program. I went to Chicago and knocked on the door of every station. But I got turned down every time.
     In one station, a kind lady said my problem was that I hadn't got enough experience. “ Get some work with a small station and work your way up,” she said.
     I went back home. I couldn't get a job there, either. Then my dad told me a businessman had opened a store and needed someone to help him. But again, I didn't get the job.
     I felt really down. “ Your luck will change,” Mom said to me. Dad lent me the car to help me to look for my job. I tried another radio station in Iowa. But the owner, a nice man, told me he had already had someone.
     As I left his office, I asked, “How can someone be a sports announcer(播音员) if he can't get a job in a radio station?”
I was waiting for the lift when I heard the man call. “ What did you mean? Do you know anything about football?” He put me in front of a microphone and asked me to try to imagine that I was giving my opinion on a football game, I succeeded.
     On my way home, Mom's words came back to me, “One day your luck will change, Son. And when it happens, it'll feel doubly(加倍的) good because of all the hard work you've had.” At that moment I knew what just what she meant.