如图所示,在正方体\(ABCD-A\)\({\,\!}_{1}\)\(B\)\({\,\!}_{1}\)\(C\)\({\,\!}_{1}\)\(D\)\({\,\!}_{1}\)中,\(E\),\(F\),\(G\),\(H\)分别是\(BC\),\(CC\)\({\,\!}_{1}\),\(C\)\({\,\!}_{1}\)\(D\)\({\,\!}_{1}\),\(A\)\({\,\!}_{1}\)\(A\)的中点\(.\)求证:
\((1)BF/\!/HD\)\({\,\!}_{1}\)
; \((2)EG/\!/\)平面\(BB\)\({\,\!}_{1}\)
\(D\)\({\,\!}_{1}\)
\(D\); \((3)\)平面\(BDF/\!/\)平面\(B\)\({\,\!}_{1}\)
\(D\)\({\,\!}_{1}\)
H.