A:Can
B:Must
C:Shall
D:Should
—Just a moment. I the paper-cutting with it.
某同学看见课桌上有一层灰,拿抹布抹课桌时,不小心手被钉子刺了一下,手臂快速收回,在此反射中神经冲动传导途径是( )
某三棱锥的三视图如图所示,则该三棱锥最长棱的棱长为____