These achievements_______ without the contribution of Qian Xuesen, a key leader of the New

China's nuclear, missile and so on.  [ ]

A. would have been unthinkable

B. would not be unthinkable

C. would be unthinkable

D. would not have been unthinkable

如果由于第三方的原因使监理工作受到阻碍或延误，以致增加了工程量或持续时间，增加的工作量应视为( )。

A．正常监理工作

B．附加监理工作

C．额外监理工作

D．新的委托监理合同工作