脊髓灰质炎是由脊髓灰质炎病毒引起的急性肠道传染病，经常侵犯的部位是（）
A.大脑
B.中脑
C.脑桥
D.延髓
E.腰髓
参考答案：E
--- ___________ --- Drop in if you have time.
A．Well, I really have to leave now.
B．I wonder if you could let me go now.
C．I’d like to go now.
D．Do you mind if I leave now?
下列物质中，互为同系物的有______，互为同分异构体的有______，互为同素异形体的有______，属于同位素的有______，是同一种物质的有______．
①液氯 ②
③白磷 ④氯气 ⑤2，2二甲基丁烷 ⑥氯水
⑦
⑧
⑨1735Cl ⑩红磷⑪1737Cl
⑫
