题目

 “Mum, can I invite my classmate Brett over to stay tomorrow night, please? It’s Friday, and we don’t have any 21      .Can I, please?” Mum was sitting at the kitchen table. Dad was 22      next to her, resting his head on his arms. Mum could 23      that James wanted so badly to have his friend over. “I’m so sorry, James,” she said. “I’m never allowed to have friends come to the house? Why, Mum?” James asked sadly, almost in 24      . “I know it’s 25       for you,” Mum said softly. “But I’m just worried other people might th下列有关实验的叙述，错误的是A. 制备细胞膜时，用蒸馏水使哺乳动物成熟的红细胞吸水涨破B. 洋葱根尖分生区细胞可以用作质壁分离的实验材料C. 鉴定蛋白质时，先加双缩脲试剂A液再加B液D. 鉴定脂肪时，使用酒精的目的是洗去浮色