—____ the workers are very tired, _____they keep on working. — They are great. We must learn from them.
John hasn’t come yet, I don’t know _____.
My house is about 25 _____ drive from the airport.
It’s said that the young trees along the river _____ two years ago.
---I don’t know when he will arrive. ---Don’t worry. I’ll call you as soon as he _____.
Mum didn’t go to bed _____ I came back home last night.