and made other people a)to see b)see c)seeing 

He saw a)by b)from c)with his own eyes

His a)observing b)observations  c)observed and calculations confirmed that Copernicus and Kepler were right.

and four of a)the b)their c)its moons,the phases of Venus and spots on the sun

Galileo used mathematical calculayion as well as observation of nature ans was the first astronomer to use a telescope.With an instrument of his own a)experiment b)construction c)calculation, Galileo observed Jupiter

But what about play and a)sport b)game c)grounds