旋后肌的作用是（）
A.屈肘关节
B.伸肘关节
C.前臂旋前
D.前臂旋后
E.肩关节旋外
参考答案：D
简述虚拟同辈群体对青少年的影响。
If you _________ reading that book, take it back to the library.
A．have finished
B．will finish
C．finished
D．are finishing
