How come you stepped into the lab with your shoes on? You’re ________to take them off before you enter it. I told you so.
What is it _____ his daughter needs most?
Who was it _____ saved the drowning girl?
“How was ______ they discovered the entrance to the underground palace?” “Totally by chance.”
___ that caused him to serve dinner an hour later than usual.
These wild flowers are so special I would do _______ I can to save them.