6. Canals have experienced a severe decline in barge traffic over the past several decades, yet with the rise in fuel costs, "shipping" by actual ships may once again become an important means of transporting
goods within the country. (no Though at the beginning of the sentence) Though难道一定要和Yet连用吗？看前面貌似说Although能和yet连用，记不清在哪里了。谢谢大牛们指点迷津~