给定一个英文文本，将其中所有单词的第一个字母变成大写字母，并返回修改后的文本。
I have a dream that my four little children will one day live in a nation where they will not be judged by the color of their skin but by the content of their character.
I Have A Dream That My Four Little Children Will One Day Live In A Nation Where They Will Not Be Judged By The Color Of Their Skin But By The Content Of Their Character.