  After a brief comment on the role of top quark in models of electroweak
symmetry breaking (EWSB), I shall discuss what we know about top quark
interaction and how to improve that knowledge. Since bottom quark is the weak
isospin partner of the top quark, its interaction with a scalar boson may also
distinguish models of EWSB. We show that Tevatron can provide useful
information through the associated production of a scalar with a bottom quark
pair.
