Directions: In the following passage, some of the words have been left out. First read the passage over and try to understand what it is about. Then fill in the blanks with the help of the alternatives given.

The Solar System has been a complicated wonder for the astronomers. This is a ___A___to which we may never have the exact answer. Man has wondered ___B___the age of the Earth ___C___ancient times. There were all kinds of ___D___that seemed to have the ___E___. But man could not begin to ___F___about the question scientifically until about 400 years ___G___, when it was proved that the ___H___ revolved round the Sun and the Earth was a ___I___of our Solar System, then scientists knew where to ___J___.  

Q:

QID H.

• 1
  Earth
• 2
  Mars
• 3
  Moon
• 4
  time