He seems too tired today, and I wonder__________ he got a good sleep last night.
The hip-pop singer is always drawing attention to issues that are usually ignored. That’s ____ is so great about him.
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 _____.