In______,people can communicate with each other by compaters.(add)

问题描述:

In______,people can communicate with each other by compaters.(add)
what_____?
A.was happen B.was taken place C.have happen D.happened

In_addition_,people can communicate with each other by compaters.(add)

what__D___?
A.was happen B.was taken place C.have happenD.happened