The volunteers worked hard ___ they collected all the trash.

• while

• until

• before

We will start the campaign ___ the school holiday begins.

• when

• before

• while

Reduce the use of plastic ___ it harms the environment.

• until

• before

• as soon as

___ the children were playing, the teachers cleaned the garden.

• When

• While

• After

They didn’t throw any waste ___ they left the picnic site.

• while

• as well as

• after

We stayed inside the house ___ the storm passed.

• until

• as soon as

• when

Plant flowers ___ you clean up the yard.

• after

• until

• while

People often save water ___ they wash dishes.

• when

• while

• until

The environment improves ___ people start recycling.

• until

• as soon as

• after

Let's wait ___ the meeting finishes to discuss our plans.

• after

• until

• before