Question

During the 1st century AD (year 100), glass had been invented and the Romans were looking through the glass and testing it.
They
(experiment) with different shapes of clear glass and one of their samples
(be) thick in the middle and thin on the edges. They
(discover) that if you
(hold) one of these "lenses"
over an object, the object would look larger.
The early simple "microscopes"
(be) really only magnifying glasses.
Sometime about the year 1590, two Dutch spectacle makers, Zaccharias Janssen and his father Hans
(start) experimenting with these lenses. They
(put)
several lenses in a tube and
(make) a very important discovery. The object near the end
of the tube
(appear) to be greatly enlarged, much larger than any simple magnifying
glass
(can) achieve by itself! They had just invented the compound microscope (which is
a microscope that uses two or more lenses).
Galileo
(hear) of their experiments and
(begin)
experimenting on his own. He
(describe) the principles of lenses and light rays and
(improve) both the microscope and telescope. He
(add) a focusing device to his microscope and of course
(go) on to explore the heavens
with his telescopes.
Anthony Leeuwenhoek of Holland
magnifying glasses in a dry goods store. He
(learn) how to make lenses. He
(get) very interested in lenses while working with
(become) so interested that he
(see) bacteria,
TOVAUVA​