Lie down on your couch and scoot around until your back is on the cushions and your legs are resting on the seat back, at a 90 degree Angle to your waist.

躺在沙发上，后背靠着坐垫，腿搁在椅背上，保持到腰90度的角度。

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Not all smooth surfaces reflect photons back to us, even though, technically, they should bounce back at the same Angle at which they hit the surface.

并非所有的光滑的表面都能将光子反射到我们的眼睛，即使从技术上讲，它们是能以击中表面的同样的角度反射回来的。

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Not all smooth surfaces reflect photons back to us, even though, technically, they should bounce back at the same Angle at which they hit the surface.

并非所有的光滑的表面都能将光子反射到我们的眼睛，即使从技术上讲，它们是能以击中表面的同样的角度反射回来的。

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