题目内容：

    Humans really do have a sixth sense that lets us detect magnetic fields (磁场), but we’re not aware we have it. It has long been known as ESP, Spider Sense, or the ability to see things before they happen. But now scientists have proved that humans really do have a sixth sense-that lets them detect magnetic fields. Tests have shown that mankind may have the same inborn sense of Earth’s magnetic field that has long been proved to exist in animals.

By putting a protein from the human retina (视网膜) into fruit flies, researchers noticed that the insect adjusted its flight path just as if its eye had not been changed. This suggests that the “sixth sense” does exist in humans but we might not be aware of it. Animals use such sight to navigate long distances during migration or, in the case of birds, to “see” where they are going. The complex tests involved examining the process by which light goes through a bird’s eye, which has interested the scientific community for more than 30 years. In the late 1970s, the physicist Klaus Schulten concluded that birds fly by relying on geomagnetically (地磁) sensitive biochemical reactions in their eyes.

Tests have shown that the special cells in the eye carry out this function using the protein cryptochrome (蛋白隐色素). Professor Reppert’s team used wild fruit flies, replacing their version of cryptochrome with the human equivalent (等价物), and then put them in a maze (迷宫) with each wing wrapped in a metal coil (金属圈). They then sent electricity through it so that the coil was magnetised in a way which is just like Earth’s electromagnetic field (电磁场). The flies responded in exactly the same way as if they had their own cryptochrome, by either avoiding the magnetic fields or moving towards them if the researchers had placed sugar nearby.

The new study was published in the journal Nature Communications.

1.What do we know about humans’ sixth sense?

A.Humans have been aware of it since ancient times.

B.It is quite different from the animals’.

C.It is the ability to predict what will happen.

D.It is also a sense developed after birth.

2.Why did researchers put a protein from the human retina into fruit flies?

A.To change fruit flies’ flight path.

B.To test if humans have a sixth sense.

C.To examine the process of birds’ flying.

D.To allow researchers detect magnetic fields.

3.What does the underlined word “it” in Paragraph 3 refer to?

A.the maze B.each wing

C.cryptochrome D.the metal coil

4.After being replaced the cryptochrome, how are the wild fruit flies?

A.They responded normally as if there had been nothing changed.

B.They couldn’t avoid the magnetic fields like before.

C.They lost the sense of direction completely.

D.They couldn’t find the sugar the researchers had placed nearby.