10.已知点P(x,y)满足$\left\{\begin{array}{l}{x-y≥-1}\\{x+y≤3}\\{y≥t}\end{array}\right.$,点Q(2,-1),若($\overrightarrow{OP}•\overrightarrow{OQ}$)min=-3,则实数t=( )
| A. | -2 | B. | -1 | C. | $\frac{3}{4}$ | D. | 3 |
7.已知一几何体的三视图如图所示,则该几何体的体积为( )

| A. | 4$-\frac{π}{6}$ | B. | 4$-\frac{π}{3}$ | C. | 4$+\frac{π}{3}$ | D. | 12$-\frac{π}{6}$ |
4.f(x)=e-x(x2-3x+1),若对于任意m,n∈[$\frac{1}{2}$,+∞),|f(m)-f(n)|<a恒成立,a的取值范围是( )
| A. | ($\frac{5}{{e}^{4}}$+$\frac{1}{2\sqrt{e}}$,+∞) | B. | ($\frac{5}{{e}^{4}}$-$\frac{1}{2\sqrt{e}}$,+∞) | C. | ($\frac{5}{{e}^{4}}$+$\frac{1}{e}$,+∞) | D. | (-$\frac{1}{e}$,$\frac{5}{{e}^{4}}$) |
3.在△ABC中,给出下列三个不等式:$\overrightarrow{AB}$$•\overrightarrow{AC}$>0,$\overrightarrow{BA}$$•\overrightarrow{BC}$>0,$\overrightarrow{CA}$$•\overrightarrow{CB}$>0,其中,能够成立的不等式( )
0 226644 226652 226658 226662 226668 226670 226674 226680 226682 226688 226694 226698 226700 226704 226710 226712 226718 226722 226724 226728 226730 226734 226736 226738 226739 226740 226742 226743 226744 226746 226748 226752 226754 226758 226760 226764 226770 226772 226778 226782 226784 226788 226794 226800 226802 226808 226812 226814 226820 226824 226830 226838 266669
| A. | 至多1个 | B. | 有且仅有1个 | C. | 至多2个 | D. | 至少2个 |