Answer
The predicted product is shown in the picture below.
Work Step by Step
There is formation of carbene with two chlorines on it. Carbenes are also formed by reactions of halogenated compounds with bases. There is dehydrohalogenation in which the hydrogen and the halogen are lost from the carbon atom. In this case the reagent is $CHCl_3$, and thus one hydrogen and one halogen is lost to give the following product.
The stereochemistry is also retained.