It is better to do waiver. 
Also, because you came from Europe, you may not use the Chinese-USA tax treaty. It means you need use that Europe country's tax treaty. You need ask them to make sure it. Or you will have trouble in the future. 
回複:我從歐洲簽J-1 到美, 我的J-1 上說"BEARER IS NOT SUBJECT TO 212(E), TWO YE
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                    回複:回複:我從歐洲簽J-1 到美, 我的J-1 上說"BEARER IS NOT SUBJECT TO 212(E), TWO
                     -chuchumao- 
                    ♂                    
                        
                    
                                                            
                    
                    
                                        
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                        01/18/2008 postreply
                                                09:41:49