什么是升降动作
参考答案：
是指在跳舞时身体的上升与下降。升降动作是在膝、踝、趾关节的屈和伸动作的转换中完成的。
— Will you be able to see Jennifer's parents when the first class is over?
— I'm afraid not. I _____ a lecture on British literature in the hall. [ ]
A. will attend
B. am attending
C. will be attending
D. am going to attend
G.655光纤的色散工程计算值是（）
A.20ps/nm.km
B.6ps/nm.km
C.17ps/nm.km
D.4ps/nm.km
