电子测量中典型的比较方法有哪些？
参考答案：
肘关节能抗一定阻力屈曲至50°则屈肘肌群肌力为MRC（）。
A.4级
B.4—级
C.3+级
D.3级
E.2+级
The single invention of the computer _______ many new professions. [ ]
A. gave a birth to
B. gave births to
C. gave birth to
D. gave birth for
