Plastic bags are not be used because they should cause much pollution

 1. Where is the lecture to take place? - I suppose in the assembly hall. 2. The meeting is to begin at five o'clock. Don't be late. 3. I have to help my friends with this work now, so I cannot go with you. 4. It was raining hard and we had to wait until it stopped raining. 5. Why didn't you tell me that I had to buy the books? 6. You wiil have to learn all the new words for the next lesson. 7. They decided that she would be to send them a telegram every tenth day. 8. Who was to go to the library to get the new books? - I was, but I couldn't because I had to finish some work at the phonetics laboratory. 9. It is raining. You have to put on your raincoat.

I clean my room every Sunday (active)The room is cleaned every Sunday.(passive)
We  made a journey last month (active)
The journey was made last month.(passive)
He will write a letter tomorrow (active)
the letters will be written tomorrow(passive)
You  are doing your homework at the moment (active)
The homework is being done at the moment(passive)
They were watching  football match at 3 o’clock yesterday (active)
The football match was being watched at 3 o`clock yesterday(passive)
I have just readthe book (active)
The book have just been read(passive)
By 4 o’clock yesterday I had presented a project (active)
A project had been presented by 4 o`clock yesterday (passive)