题目

—He is eager to try something he has never tried before.     —Oh, I see. That’s _______ he’s different from others. A. when               B. where     C. how       D. what 答案：B18．方程组$\left\{\begin{array}{l}{x-2y=9}\\{3x+2y=-1}\end{array}\right.$的解是$\left\{\begin{array}{l}{x=2}\\{y=-\frac{7}{2}}\end{array}\right.$．