蒲公英叶序为基生叶序，玉米的叶序为互生叶序，夹竹桃的叶序为轮生叶序。
参考答案：对
I _____ Beijing in a few days. Do you know when the earliest plane _____. [ ]
A. leaves; takes off
B. am leaving; is taking off
C. am leaving; takes off
D. leave; is taking off
双层双面只读DVD盘片的存储容量可以达到______。
A．4.7GB B．8.5GB C．17GB D．6.6GB
