A:They are thirteen dollars.
B:They're black.
C:It's only four dollars.
在等边△ABC中,CD是∠ACB的平分线,过D作DE∥BC交AC于E,若△ABC的边长为a,则△ADE的周长为 ( )
如图所示,是一定质量的某物质熔化时温度随时间变化的图像,由图像可知( )
Mrs Read the cleaning every day.
用配方法解方程x2-2x-7=0时,原方程应变形为 ( )