12.某程序如图所示,该程序运行后输出的最后一个数是( )

| A. | $\frac{17}{16}$ | B. | $\frac{9}{8}$ | C. | $\frac{5}{4}$ | D. | $\frac{3}{2}$ |
5.已知a,b∈R,定义运算“?”:a?b=$\left\{\begin{array}{l}{aa-b≤1}\\{ba-b>1}\end{array}\right.$,函数f(x)=(x2-2)?(x-1),x∈R,若方程f(x)-a=0只有两个不同实数根,则实数a的取值范围是( )
| A. | [-2,-1]∪(1,2) | B. | (-2,-1]∪(1,2] | C. | [-2,-1]∪[1,2] | D. | (-2,-1]∪(1,2) |
4.已知长方体ABCD-A1B1C1D1中,B1C,C1D与底面ABCD所成的角分别为60°和45°,则异面直线B1C和C1D所成角的余弦值为( )
| A. | $\frac{\sqrt{6}}{4}$ | B. | $\frac{1}{4}$ | C. | $\frac{\sqrt{2}}{6}$ | D. | $\frac{\sqrt{3}}{6}$ |
3.已知M(-4,0),N(0,-3),P(x,y)的坐标x,y满足$\left\{\begin{array}{l}{x≥0}\\{y≥0}\\{3x+4y≤12}\end{array}\right.$,则△PMN面积的取值范围是( )
0 238187 238195 238201 238205 238211 238213 238217 238223 238225 238231 238237 238241 238243 238247 238253 238255 238261 238265 238267 238271 238273 238277 238279 238281 238282 238283 238285 238286 238287 238289 238291 238295 238297 238301 238303 238307 238313 238315 238321 238325 238327 238331 238337 238343 238345 238351 238355 238357 238363 238367 238373 238381 266669
| A. | [12,24] | B. | [12,25] | C. | [6,12] | D. | [6,$\frac{25}{2}$] |