在图层控制面板上，哪个图层的上下位置无法改变：（ ）
A．刚新建的新图层
B．背景图层
C．背景图层上方的图层
D．隐藏图层
参考答案：B
连词成句。
1. are what you now doing ?
_________________________________________
2. loudly baby crying the is .
3. would like what . drink to you ?
4. are in there many the people street .
5. scared feels Li Ming too .
EDTA是六元酸，在溶液中有七种存在形态。
