Passive of modal verbs

They must wash the towels every day.

• The towels must be wash every day.

• The towels must be washed every day.

A molecular minicry can cause a heart attack.

• A heart attack can be caused by a molecular minicry.

• A heart attack can is cause by a molecular minicry.

Roberto has to serve this chicken.

• This chicken has to be served by Roberto.

• These chicken have to be served by Roberto.

Guatemalans could elect a new goverment next year.

• A new goverment could is elect by Guatemalans next year.

• A new goverment could be elected by Guatemalans next year.

I may explore other planets in 2030.

• Other planets may be explored by me in 2030.

• Other planet may is explore by me on 2030.

They shouldn´t make movies with violent scenes.

• Movies for violent scenes shouldn't be make.

• Movies with violent scenes shouldn't be made.