Nuclear ______ be really dangerous at times even though it’s a nice energy in general.

I hear the plane of MH370 has been found!—ReallyI wonder if some people are still alive.

It is _____ classroom that can hold 100 students. [ ]

It ____ last night, for the ground is wet now.

How often arethe Olympic Games held —______fouryears. A. EveryB. Each C.In D. For