He has promised me that upon my return he       for me at the airport.

--The window is dirty.----I know. It ______ for weeks.

The fact that so many people still smoke in public places ______ we may need a nationwide campaign to raise awareness of the risks of smoking.

With more forests being destroyed, huge quantities of good earth _______ each year.

--How did he get infected? --She ____the viruses without any protection.