_______, you need to give all you have and try your best.

A．Being a winner.

B．To be a winner

C．Be a winner

D．Having been a winner

当室内燃气管道选用不锈钢管时，薄壁不锈钢管应采用( )连接方式。

A．钎焊
B．承插式管件氩弧焊或卡套式管件机械
C．法兰
D．螺纹