穿过道路、铁路的乙炔管道最好用大于路边缘2m长，加无缝钢管作保护套管，埋深分别在0.7m、1.2m以下。
参考答案：对
The job is great in terms of salary . It has its disadvantages, _______ .
A．though
B．however
C．even
D．therefore
与门至少有二个输入，有（）输出。
