19.
如图,将一个长为10cm,宽为8cm的矩形纸片先按照从左向右对折,再按照从下向上的方向对折,沿所得矩形两邻边中点的连线(虚线)剪下(如图(1)),再打开,得到如图(2)所示的小菱形的面积为( )
| A. | 10cm2 | B. | 20cm2 | C. | 40cm2 | D. | 80cm2 |
16.若不等式组$\left\{\begin{array}{l}{2x-1<1}\\{x+1>a}\end{array}\right.$恰有两个整数解,则a的取值范围是( )
0 288697 288705 288711 288715 288721 288723 288727 288733 288735 288741 288747 288751 288753 288757 288763 288765 288771 288775 288777 288781 288783 288787 288789 288791 288792 288793 288795 288796 288797 288799 288801 288805 288807 288811 288813 288817 288823 288825 288831 288835 288837 288841 288847 288853 288855 288861 288865 288867 288873 288877 288883 288891 366461
| A. | -1≤a<0 | B. | -1<a≤0 | C. | -1≤a≤0 | D. | -1<a<0 |