题目

68. Mind you. Don’t bump your head on the low________when you go upstairs for sleep. A.top                     B. tip                     C. bottom                D. Ceiling 答案：D血浆具有的功能是A. 吞噬病毒                       B．止血和凝血     C．运载血细胞、运输养料和废物      D．运输氧气