Then, about 400 years ago, the microscope was invented, and for the first time, scientists could see objects as tiny as a cell.
(the microscope; was invented; T:Then; T:about 400 years ago) (scientists; could see; objects as tiny as a cell; T:for the first time)
the microscope scientists
was invented could see
T:Then T:about 400 years ago
objects as tiny as a cell T:for the first time