A:①②
B:②③
C:②④
D:③④
小明为妈妈准备了一份晚餐:米饭、红烧鲫鱼、小炒黄牛肉、鸡蛋汤.为了使营养搭配更合理,应增加( )
如图所示,当开关S闭合时,螺线管与左边始终静止的磁铁相互吸引。请在图中画出螺线管的绕线;当滑动变阻器的滑片P由左端滑动时,左端磁铁所受的摩擦力将( )
—I hear that Tom's sister is a teacher here. —Yes, the girl is standing under the tree is his sister.