Recorded history has taught us ______.

A．the force of the electromagnetic field is too weak to be harmful
B．the force of the electromagnetic field is weaker than the electric field that the cells generate
C．electromagnetic field may affect health
D．only more powerful radiation can knock electron out of human body

A．Because it may stir a great deal of debate among the Bush Administration.
B．Bemuse every unit of the modern military has depended on the heavy use of some kind of electronic equipment.
C．Bemuse the Pentagon's concern was understandable.
D．Because they had different arguments.