溶液
双缩脲试剂
碘液
斐林试剂
甲
+
﹣
乙
++
甲、乙混合
注:“+”显色,“++”显色更深;“﹣”不显色.
A:甲溶液含有淀粉
B:乙溶液含有还原糖
C:混合溶液不含淀粉
D:混合溶液含有淀粉酶
如图所示,小球在轻弹簧和水平轻绳的拉力作用下处于静止状态.弹簧与竖直方向的夹角θ=37°,弹簧的拉力F=10N,伸长量为△x=0.01m,sin37°=0.6,cos37°=0.8.
-- Is it to protect the earth against heavy pollution?
-- No, I don't think so. If everybody takes actions now, it will become better.
读图,回答.