They investigate rusting, and they observe and collect the gas formed by mixing an effervescent tablet in water.
(They; investigate; rusting) (they; observe; ) (they; collect; the gas formed by mixing an effervescent tablet in water) (the gas; formed; by mixing an effervescent tablet in water)
They they they the gas
investigate observe collect formed
rusting
the gas formed by mixing an effervescent tablet in water
by mixing an effervescent tablet in water