假设你是育才中学学生会主席李华。针对目前一些地方血库纷纷告急这一情况，请参照以下提示，用英文写一份倡议书，提倡无偿献血(donate blood for free)。
● 社会上对献血的错误认识；
● 指出献血的意义；
● 开展相关活动。
注意：
1.字数120—150；
2.可以适当增加细节，以使行文连贯；
3.开头与结尾已为你写好。
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Boys and girls,
Recently some blood banks across the country are reported to be short of blood supplies.                                                                            
                                                                                  
                                                                                  
                                                                                  
                                                                                  
                                                                                  
                                                                                  
                                                                                  
                                                                                  
                                                                                  
                                                                                  
                                                                                  
                                                                                  
                                                                                  
Students Union