如果长方体的长为3a﹣4，宽为2a，高为a，则它的体积是（　　）

若变量$x,y$满足约束条件$\{\begin{array}{c}x+y-3\le 0\\ x-y+1\ge 0\\ y\ge 1\end{array}$，则$z=2x-y$的最大值为（   ）

    Hi! I'm Tony. I love 1! I always get up late on weekends. For breakfast, I only have 2. It's usually an apple. I have a big lunch. After lunch, I like to eat ice-cream. It 3 good. In the afternoon，I like to 4. I usually play basketball. Sometimes I swim. In the evening, I clean the house—I like 5rooms. I always go to bed late，at about 23: 00.

    But my sister doesn't like weekends. She has a job in a big store and she always works on weekends. She never goes out 6 her friends. She usually 7 home from work at 22:00. she 8 in bed after she takes a shower. But don't ask her 9 she reads. She always falls asleep (睡着) after 10 one or two pages (页).