—Susan, what are the advantages of MP5 players?
—Mom, they are smaller and lighter ______ they can be carried very easily.
A. unless B. if C. until D. so that
D。对连词的考查。前者问MP5的优势是什么,答者说“妈妈,他们更小而且更轻,以至于他们可以轻松地被懈怠。”后句是前句的目的,so that表示目的,“以至于”。unless除非,if如果,until直到。所以答案选D.