It isn’t clear_____ is to blame.We need to find a solution to the problem first.
We must take measures to stop various kinds of pollution ______ the environment gets worse.
The rumor has been confirmed __________ UN peacekeeping forces would take operations in the region .
Hearing his friend calling him , out __________ .
Whatever happens, you may depend on ________ that I will be with you.
__________ in the new on-line game , he missed the final boarding call of his flight .