—Are you coming to Jeff's party?—I'm not sure. I _______ go to the concert instead.
The thief looked around every now and then _____ he knew he was being followed.
He insisted ______ alone in the mountain.
Xi’an was attacked by such a terrible smog _____ few residents had ever experienced before.
____ an important decision more on emotion than on reason, you will regret it sooner or later.
The way _____ was thought of by him was similar to the way ______ we carried it out.