He says all _______ tried their best and that all that can be done _______ been done.
It is recognized that the part ___ the UN plays in international relations is important.
Who would you rather ______ with the teacher about the problem?
When _____ the letter, tears came to her eyes.
Did he find _____ hard to learn a foreign language?
The computer system _____suddenly while Paul was searching for information on the Internet.