A:自我疏导
B:寻求帮助
C:乐观向上
D:及时醒悟
如图为电动机和发电机模型,其中图____ (选题“甲”或“乙”)为电动机模型,其工作原理是____ ;电动机工作时,能够使线圈平稳,连续不停地转动下去是靠____ 实现的.
—Do you know______next Friday, Lily?
—If it doesn't rain, we will.
—The cake smells ___________ bad.
—It goes ___________ easily if you don't keep it in the fridge.
若二次根式1+2x有意义,则x的取值范围为( )