填空题

The modem society has witnessed amazing development in astrology. In recent years scientific investigation of comets has (36) because of a growing interest in the origin of the sun and (37) . Scientists want to learn how comets are formed. They think that such information will be (38) to man’s understanding of the origin of the (39) system.
The word "comet" comes from the Greek and means "hairy object". In history comets have a special place. People believed that they brought news of death, (40) or military victories.
The tails of comets provide (41) with spectacular sights at night. Comets tails are millions of kilometers long. The tail (42) reaches lengths of 250 kilometers and more.
There was a written (43) of comet as early as 1770 B.C. The Chinese kept careful record and so did the Babylonians. (44) .
The most famous comet in history is called Halley’s Comet. (45) .It was named after Edmond Halley, an English scientist. (46) The comet appeared in 1758, as he predicted, 16 years after his death and will return again in 1986.