David_______ all night in order to watch the football match between France and Italy.
A:put up
B:stayed up
C:got up
D:showed up
a、b、c 三种物质的溶解度曲线如图所示.取等质量t2℃的 a、b、c 三种物质的饱和溶液,分别蒸发等量水后恢复至t2℃.下列说法不正确的是( )
已知关于x的方程(a-1)x2-2x+1=0有实数根,则a的取值范围是( )