-----How long do you think it will be _____man can finally solve the problem of cancer?------Well.it depends.
It rained heavily in the south,________ serious flooding in several provinces.
Bring the plants into a warm room _____ they will soon open.
When I got home, I _____ I had left my wallet in the taxi
The two men are so alike that strangers find _____ difficult to tell one from the other.
As is known to all, _____USA is _____ biggest developed country in the world.