卡钳是一种（）测量的量具。
A、直接
B、间接
C、混合
D、不确定
参考答案：B
I’ve been playing the piano for four hours and I am ________ it.
A．tired of
B．tired in
C．tired on
D．tired through
腓肠肌神经支配的对应关系是（）
A.L2
B.L3
C.L4
D.L5
E.S1
