Studying the Top Quark via the W-Gluon Fusion Process

We show that studying the single top quark production via the $W$--gluon fusion process can provide unique information on: (i) the measurement of the decay width $\width$; (ii) probing the symmetry breaking mechanism by measuring the form factor of~\tbW; (iii) testing the Effective--$W$ Approximation prior to supercolliders; (iv) testing CP violation by observing different production rates of $\bar p p \ra t X $ and $\bar p p \ra \bar t X$; (v) testing CP violation from the almost hundred percent longitudinally polarized top quark decay; in addition to the measurement of the top quark mass. In contrast to the recent claim by R. K. Ellis and S. Parke, we show that this process is extremely useful at the Tevatron.