What is typical for the comets' nature?

1.   ?    they consist of solid parts
2.   ?    their chemical composition is similar to the chemical composition of the bodies which cause meteors
3.   ?    they consist of solid parts and their chemical copmosition is similar to the meteors' chemical composition;

What is the model of a comet like?

1.   ?    their nucleus consists of frozen gases and parts of dust
2.   ?    they consist of a nucleus and a tail
3.   ?    they consist of solid parts
4.   ?    none of these answers is true

When the next passage of the Halley's comet is going to be?

1.   ?    2005
2.   ?    2024
3.   ?    2062
4.   ?    2087