—Mrs. Black, I'm afraid that I'll fail the exam.
—________, dear! Take it easy. I'm sure you'll pass it.
A:Sorry to hear that
B:Come on
C:All right
D:Good job
用减法验算294+406=700的算式是( )。
- Who is your best friend? ( )
- __________
下列化学式表示的物质中,属于离子晶体并且含有非极性共价键的是( )