tiantian wrote
 Resolve3To8(in=address, out=resolve);
 Mux16(a=false, b=true, sel=resolve[0], out=resolve0); 
Resolve3To8 is a chip written by me. the resolve is a 8 array. why it show the error "sub bus of an internal node may not be used", when i insert this file to the Hardware simulator?
 
You cannot use the [] syntax on internal buses like 'resolve'.  What you need to do is use multiple connections to the Resolve3To8's 'out' bus:
    Resolve3To8(in=address, out[0]=r0, out[1]=r1, out[2]=...);
    Mux16(a=false, b=true, sel=r0, out=resolve0);
--Mark