The schoolboy regretted _______ after he didn't pass his exam.
_______ she couldn’t understand was ______ fewer and fewer students showed interest in her lessons.
It is pretty well understood _______ controls the flow of carbon dioxide in and out the atmosphere today.
Country life gives him peace and quiet, which is ______ he can’t enjoy while living in big cities.
“What were you trying to prove to the police?” “___ I was last night.”
It has come to my notice _______ some of you have missed classes.