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