Thus, the telescope must have a lens that is at least 80 mm (3 inches) for a refracting telescope or a mirror that is a least 6 inches for a reflecting telescope.
(the telescope; must have; a lens that is at least 80 mm (3 inches) for a refracting telescope or a mirror) (a lens; is; at least 80 mm) (a mirror; is; a least 6 inches for a reflecting telescope)
the telescope a lens a mirror
must have is is
a lens that is at least 80 mm (3 inches) for a refracting telescope or a mirror
at least 80 mm
a least 6 inches for a reflecting telescope