肌肉收缩的形式有（）
A.单收缩
B.等长收缩
C.完全强直收缩
D.等张收缩
E.不完全强直收缩
参考答案：A, B, C, D, E
72. At the beginning, I had some difficulty with my English, and my teacher pulled me ______.
A．down
B．over
C．up
D．Through
当水松纸导纸辊表面积垢、磨损或转动不灵活时，会造成水松纸走偏，影响水松纸的正常供给。
