组成植物种子的主要结构是
①种皮②胚芽③胚轴④胚根⑤子叶⑥胚乳 [ ]
A．①②③④
B．③④⑤⑥
C．②③④⑤
D．①②⑤⑥
答案：C
先观察，找出规律后再填空．
21×9=189
321×9=2889
4321×9=38889．
54321×9=______
987654321×9=______．
Nowadays ________ Internet is becoming increasingly popular and new high speed broadband network was recently started.
A．a; the
B．the; a
C．a; a
D．the; the
