组成臂丛上干的神经是（）
A.颈5
B.颈5、6
C.颈7
D.颈8
E.颈8、胸1
参考答案：B
As a student of Senior Three, he has very little free time __ he can spend developing his own interest.
A．when
B．in which
C．at which
D．that
对采用全野外数字测图方法测绘的大比例数字地形图进行数学精度的实地检侧时，一般每幅图至少选取（）个点采用散点法监测点位中误差。
A.5
B.10
C.15
D.20
