Professionals involving in such development should have a unique sense of innovation, the ability to assimilate new information, outstanding development skills and a striving sense of international cooperation.

A．involved to

B．involved as

C．involving as

D．involved in

交流弧焊机变压器的一次侧电源线长度不应大于多少米？电焊机械的二次线电缆长度不应大于多少米？