题干
Mr. Green will arrive here and give us a speech ___________ the morning of December 22nd.
A：in
B：on
C：at
D：before
答案(点此获取答案解析）
B
Mr. Green will arrive here and give us a speech ___________ the morning of December 22nd.
A：in
B：on
C：at
D：before
( )
