Jane can't attend the meeting at 3 o'clock this afternoon because she ______ a class at that time.
A：will teach
B：would teach
C：has taught
D：will be teaching
下列家用电器．主要利用电流热效应工作的是（ ）
海拔一般在200米以下，地面平坦或起伏较小的地形是（ ）
下列有关生物膜的说法正确的是( )
—Yes, great changes have taken place these years.
