Reported by Andrey Melnikov <vafilor@gmail.com>.
@code{.SECONDARY} make would rebuild @file{hello.o} then rebuild
@file{hello.bin} even though the source files had not changed. By declaring
@file{hello.o} as @code{.SECONDARY} @code{make} will not need to rebuild it
-and won't need to rebuild @file{hello.bin} either. Of course, of one of the
+and won't need to rebuild @file{hello.bin} either. Of course, if one of the
source files @emph{were} updated then all object files would be rebuilt so
that the creation of @file{hello.bin} could succeed.