CANADA STOCKS-TSX slips after Yellen comments, Ukraine tensions

* TSX down 30.35 points, or 0.20 percent, at 15,525.74 * Five of 10 main index sectors decline * Energy shares slip with oil price By John Tilak TORONTO, Aug 22 (Reuters) - Canada's main stock index slipped on Friday in a choppy market after U.S. Federal Reserve Chair Janet Yellen called for a "pragmatic" approach that gives the central bank the flexibility to determine next steps based on evolving economic data. In a speech to policymakers, Yellen said that U.S. labor marke