------ elephant is ----- useful animal to human beings.填神马?

------ elephant is ----- useful animal to human beings.填神马? The elephant is _____ useful animal to human beings.A.a B.an ( )elephant is ( )useful animal to p Water is to fish ---------oxygen is to human beings.横县应该填什么, human beings to program ___ elephant is ___ useful animal.A.An;an B.An;a C.Thn;an D. ( )horse is ( )useful animal. human beings are human beings water is very essential for human beings Since human beings depend to a great cats never fail to fascinate human beings Lungs are to human beings ___ the forest is to the earth.