题目

My money_____, I must go to the bank to draw some of the savings out before I have none in hand. A. has run out      B. has been run outC. is running out   D. is being run out 答案：C。 解析: 从后半句“在我手头的钱还没用完之前，我得先去银行取些出来”可知，前半句应是：我的钱快用完了。故用进行时态表示现阶段的状态。毛细血管壁和肺泡壁都是由一层扁平的上皮细胞构成，这有利于进行________．