请小朋友把窗子擦干净，可以说：

    I'm Sally.I have three new teachers.A Chinese teacher，a maths teacher， and an art teacher.My Chinese teacher is Miss Zhang.She's pretty and young.My maths teacher is Mrs Liu.She's tall and thin.My art teacher is Mr Sun.He's tall and strong.He's very kind.

电话之间互相通话时，一般都是通过____ 来转接的，这样可以提高线路的利用率，电话通信存在____ 信号和____ 信号两种．

— Must we take out the trashwww.dearedu.com(倒垃圾) now?

—________. You can do it after class.