输气管线穿越铁路宜采用钢筋混凝土套管（）。
A.顶管施工
B.开槽施工
C.机械施工
D.排水施工
参考答案：A
Along with the email was my brother’s promise ______ I came first in the competition, he would buy me an MP4.
A．what
B．that
C．that if
D．whether
A．导线中电流变大
B．线框向下平动
C．线框以ab边为轴转动
D．线框向右平动
