已知2x-y=10，则2y-4x的值为 [ ]
A.10
B.20
C.-10
D.-20
答案：D
If children are asked to help with housework, they will feel needed. ______, they will learn to take care of themselves.
A．On the contrary
B．In a word
C．That is to say
D．What’s more
在幻灯片放映过程中如何结束放映？
