只要给仙人掌空气和阳光，仙人掌就能成活。[ ]
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Teachers have to constantly update their knowledge in order to maintain their professional ______.
A．consequence
B．independence
C．competence
D．intelligence
跖反射的反射中枢位于（）
A.腰髓1～2节
B.腰髓2～4节
C.骶髓1～2节
D.骶髓2～4节
E.骶髓2～3节
