I have ______ many different friends ______ it is hard to choose just one best friend.
With the world changing fast, we have something new _____ with all by ourselves every day.
—Have you been to the Great Wall?—Perhaps not in my memory. ________, it might have been during my early childhood.
The question that puzzled them is ____ they can get rid of the air pollution in the area.
Teachers have to constantly update their knowledge in order to maintain their professional _____.
“I don’t think it’s my _______ that the TV blew up. I just turned it on. That’s all.” said the boy.