A．Because more and more people move into big new houses.

B．Because many old people sell their house after their children leave.

C．Because people want to sell the old house to get money and build their own house.

D．Because children often ask their parents to sell the old house.

补偿电缆引接线安装采用塞钉安装时，塞钉头露出钢轨（）；当采用电容销钉安装时，销钉螺纹部分露出轨腰长度为14mm±1mm。