是focus on doing，没有focus on do的说法。
focus on doing是“集中精力做某事”的意思，具体的句式是Focus on doing sth。
例如：
So then I thought maybe I should just focus on doing something I really care about do it really well, and not to worry about what other people think.
所以我当时想我也许就专注在我真正在乎的一项事情上，并把它做得很好，不要在意别人会怎么想
