单项选择题

Scientists have discovered in the past few years that ______.

A．the exposure of DNA to the public is unnecessary
B．the tiny cell in DNA is a neat little machine
C．man actually knows nothing about DNA
D．man has much to learn about DNA

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热门试题

单项选择题

According to the passage, a teacher's duty is to ______.

A．provide students with help when it is needed
B．find out students' mistakes and correcting them
C．teach students knowledge essential for their future life
D．help students find out correct answers

单项选择题

The passage suggests that learning to speak and learning to fide a bicycle ______.

A．provide essential skills for learning to grow
B．need a lot of teaching and correction
C．are similar in that they are learnt by practicing and making changes
D．are quite different in the way they are picked up naturally