It is nearly time to go.

副词 nearly 修饰名词time。有些副词可用来修饰不定代词、数词和时间名词。表示“接近；几乎；差不多” 之意。常用的这类副词有about, almost, nearly 等。例如：

In the UK, students finish school and go home at about three o 'clock. 

在英国，学生们大约三点放学回家。

We arrived at nearly ten o'clock.

我们差不多十点钟到达。

Nearly anyone present at the meeting was an expert on bird flu.

参加这次会议的人几乎都是禽流感方面的专家。

I learned three foreign languages at college,but now I have forgotten almost all of them.

我上大学时学过三门外语，可现在几乎全忘了。