虚活动的主要作用是表明前后活动之间的关系。（）
参考答案：对
Not until ___to do my homework ____ how much time I had wasted playing computer games.
A．I began; I realized
B．I began; did I realize
C．did I begin; I realized
D．did I begin; did I realize
子女为什么不得擅自侵占、改变老年人的住房产权关系？
