---___________ you sing these English songs?
---No, we can't.
A:Are
B:Can
C:Does
D:Have
在式子1a、2xyπ、3a2b3c4、56+x、x7+y8、9x+10y中,分式的个数有( )
When I arrived at the office, the meeting ____ (be) on for ten minutes.