设m，n表示不同的直线，α，β表示不同的平面，且m，n⊂α．则“α∥β”是“m∥β且n∥β”的（　　）

A．充分但不必要条件

B．必要但不充分条件

C．充要条件

D．既不充分又不必要条件

It was now clear that no such weapons were manufactured and none been found.

A. was found



B. were founded
C. has been found


D. have been founded