如图,已知AB⊥CD垂足为O,EF经过点O.如果∠1=30°,则∠2等于( )
A:30°
B:45°
C:60°
D:90°
节假日期间,很多人喜欢上土岭的观音山上踏青.下列能构成观音山生态系统的是山中所有的( )
In America, a friend inviting you to a restaurant doesn't mean that he or she will pay for the meal ______ you are told ahead.
Mr. Black: __________
Mike: Very well, thank you.