题目

He rushed into the classroom when Mr. Simpson ______ about American history. A) talked       B) had talked   C) would talk   D) was talking 答案：D某细胞中的含水量为：自由水∶结合水=94∶6，在水分总量不变的情况下，新陈代谢速度加快，则两种水的含量变化是（   ）A．自由水减少，结合水增多B．自由水增多，结合水减少C．自由水和结合水均减少D．自由水和结合水均保持不变