30. The coal we use today should _____ plants and trees.
---May I take your order now? ---_______.
She was so angry at all ______ I was doing ______ she walked out.
The old woman had a letter from her son in the army_____ to her.
It was ______ the old clock that the old man spent the whole morning at home.
The joke told by Tom made us______, so our maths teacher couldn’t make himself______.