下颈椎损伤可引起( )
A．双上肢痉挛性瘫痪B．双下肢痉挛性瘫痪C．四肢痉挛性瘫痪D．四肢迟缓性瘫痪E．双下肢迟缓性瘫痪
参考答案：B
Our bodies are strengthened by exercising._____, our minds are developed by learning. [ ]
A. Likely
B. Similarly
C. Probably
D. Therefore
空气污染的主要来源是 [ ]
A.火山爆发
B.煤和石油等矿物燃料的燃烧，和工厂的废气
C.动、植物的呼吸
D.植物的光合作用
