and it is now celebrated as Independence Day also called the Fourth of July. [] during which the World Trade Towers in New York City were completely destroyed and the Pentagon in Washington, DC was severely damaged. [] 11 Southern slave-keeping states declared their separation from the US and formed the Confederacy. They fought against the Northern States also known as the Union - the states where slavery had been abolished. [] after the surprise Japanese attack on the US Naval base in Pearl Harbour, Hawaii

Дано:

• and it is now celebrated as Independence Day also called the Fourth of July.
• [x] during which the World Trade Towers in New York City were completely destroyed and the Pentagon in Washington, DC was severely damaged.
• [x] 11 Southern slave-keeping states declared their separation from the US and formed the Confederacy. They fought against the Northern States also known as the Union - the states where slavery had been abolished.
• [x] after the surprise Japanese attack on the US Naval base in Pearl Harbour, Hawaii

Обоснование:

• Первое предложение является утверждением о праздновании Дня Независимости.
• Второе предложение описывает события 11 сентября 2001 года, которые привели к уничтожению Всемирного торгового центра и атаке на Пентагон.
• Третье предложение описывает начало Гражданской войны в США, когда южные штаты отделились и сформировали Конфедерацию.
• Четвертое предложение описывает нападение на Пёрл-Харбор, которое привело к вступлению США во Вторую мировую войну.

Ответ: Отмечены события, связанные с 11 сентября 2001 года, началом Гражданской войны и нападением на Пёрл-Харбор.