等张收缩的特点是（）
A.产生位移
B.发生在离体骨骼肌
C.是单收缩
D.可做功
E.可维持姿势
参考答案：A, D
设自然数n1＞n2，且n12-n22=79，则n1=______，n2=______．
_____ comes from Japan. He speaks ______.
A Japanese, Japanese B Japanese, a Japanese
C A Japanese , Japanese D A Japanese , Japaneses
