acting as a screen between the Sun and the Earth's surface
问题描述：
acting as a screen between the Sun and the Earth's surface
意思是 像一层屏幕一样的在太阳表面和地球表面的中间行动吗？
答
在太阳表面和地球表面的之间起到一个屏幕的作用.
act在此意思是起到像什么一样的作用,
例如：
The forest will act as a defense against desert dust.
森林能起防御沙漠灰沙的作用.