A U.S. national flag and flowers are placed on a plate on which the names of 9/11 victims were inscribed at the National September 11 Memorial and Museum in New York, the United States, Sept. 11, 2019. People paid their tributes here on Wednesday to mourn the victims of the 9/11 terrorist attacks which happened 18 years ago and claimed thousands of lives. (Xinhua/Li Rui)