I ______ my English teacher since I left university.
A:didn't see
B:haven't seen
C:won't see
D:don't see
There _______ a boy and two girls in the music room, they are singing.
下列四种能源中属于二次能源的是( )
材料一:北京市提出了“3+2”首都经济圈及“一轴、两核、三区”为框架的京津冀都市圈发展战略构想,并称为“京三角”。它与“长三角”“珠三角”一起,并列为中国三大经济圈。
材料二:如图1为中国主要工业基地分布图.图2甲乙丙为“京三角”“长三角”“珠三角”图。