A．

Light and shadow are friends． They usually go together． We receive light every day． At the same time，we produce shadow．

Light cannot shine through you． Your body stops it from passing． There is 'a dark spot on the ground next to you． The light cannot reach the dark spot． This is your shadow．

A．t noon the sun shines over your head． Your body stops very little light from reaching the ground． So your shadow is quite short．

B．ut in early morning or late afternoon the sun is low in the sky．Its light moves over more of your body．Then your shadow is quite long． Your body keeps a lot of light from reaching the ground．

We love light，especially sunlight． Without sunlight，life on the earth is impossible．Most of us like to stand in the shadow of a tree in summer． But some people are afraid of their own shadow at night． They do not want to walk in a dark street． They do not want to see the shad-ow，either． But still light and shadow usually go together．( )21． The sentence "Light and shadow are friends． " means ________ ．

A． the shadow produce light

B． the light usually follows the shadow

C． they usually get on well with each other

D． They are always together，when we get light，we can get shadow．