Fill in the correct passive form of the verbs in bracket

Fill in the correct passive form of the verbs in bracket. 1) The Eiffel Tower … . (visit) by about six milliom people each year. 2) The exhibits in themuseum must not … (touch) 3) Luckily, the fire … (put out) before anyone got hurt. 4) Jason believes that all types of public transport … (power) by natural gas in the future.