How can I deduce long sentences to find their meaning. I am facing this problem when I am preparing for GRE . As I am not a native English speaker, I feel lost while I am reading those long convoluted sentences, like
It would seem unlikely that evolution should discriminate against sinistral snails if sinistral and dextral snails are exact mirror images, for any disadvantage that a sinistral twist in itself could confer on its possessor is almost inconceivable.
Though I don't have problem with vocabulary, but I feel lost. Is there any technique to understand them easily?