下列哪些不是二氧化碳对呼吸的调节途径()
A.直接刺激呼吸中枢
B.刺激颈动脉体和主动脉体
C.加强牵张反射
D.刺激延髓化学敏感区
E.刺激外周呼吸肌
参考答案:A, C, E
在下面平面图形中,对称轴最多的是( )
A.长方形
B.正方形
C.等边三角形
D.扇形
_______ I went to the South Lake in Hanzhong, I was deeply impressed with its beautiful scenery.
A.For the first time
B.The first time
C.At first
D.It was the first time