题目

Progress so far has been very good. We are, _____, confident that the work will be completed on time. A. besides                     B. however C. otherwise                 D. therefore 答案：D鸡蛋握在手中，使劲握蛋壳，因为手指和蛋壳接触面积________，压强________，所以蛋壳一般不破碎，但将它在桌边轻敲一下，蛋壳就破了，主要是因为蛋壳和桌边的接触面积________，压强________．