Now, even cars can ____ (购买) on the Internet with just a few clicks of a mouse.
下列一元二次方程中两根之和为2的是
如图所示,物体A和B的重力分别为10N和3N,不计弹簧秤和细线的重力和一切摩擦,则弹簧秤的读数为( )