So as you can see，it is a polite thing to make the question(240) ______at the very beginning.
A.easy
B.clear
C.clean
D.careful
正确答案是D
So as you can see，it is a polite thing to make the question(240) ______at the very beginning.
A.easy
B.clear
C.clean
D.careful
正确答案是D