单侧隐睾手术治疗应在()。
A.2岁以前
B.3~6岁
C.7~10岁
D.青春期
E.婚后影响生育时
参考答案:A
There has been great ___________ in his English this year.
A.improve
B.progressing
C.improvement
D.improving
如图所示,线圈平面与水平方向成θ角,磁感线竖直向下,设磁感应强度为B,线圈面积为S,则穿过线圈的磁通量φ=___________。