题目

_________ that you return it back to me today, I can lend my bike to you. A. If          B. Provided C. Supposed        D. Once 答案：B人体组织液中的O2要进入组织细胞中参与氧化分解有机物，这些O2需要通过几层磷脂分子层A.1B.2C.3D.6