根据句意和首字母完成单词

　　What does HCS s________ for?

Choose the words or expressions and complete the passage(选择最恰当的单词或词语，完成短文。用A、B、C或D表示)

　　What is blood? It is the red liquid which comes out of your finger where you cut it.

　　There are about thirteen pints(品脱) of blood in a man's body. He can 　　1　　 a pint of blood at a time to the blood bank for the use of other people who may need it. A healthy body makes up the pint of blood quickly.

　　What does blood do for us? It 　　2　　 food to all parts of our bodies and takes waste away from them. All parts of our bodies are made up of cells(细胞). These cells, which are very small, all need food all the time. No one 　　3　　 cells before the invention of microscope(显微镜). Before then no one could make pictures of cells because no one could see them.

　　What makes the blood move round the body? The heart sends it round. 　　4　　 man's heart is the size of his shut hand.

　　The heart is a pump(泵). It pumps blood and sends it round the body. The heart has four rooms with doors between them. It pumps blood in and out 5these doors by changing the size of the rooms so that the doors open and shut. The heart keeps a stream(一股) of blood 　　6　　 all round the body and back again to itself. The heart is a very important part of one's body. When it stops beating, one will die very soon.

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　　根据提示完成下列句子

　　What does she ________ _________ (看起来像)