just now用于什么时态

  now可用作副词，表示现在，马上，此刻。用作名词时，有现在，此刻的意思；用作形容词时有现在的，目前的等含义。

  一.now用作副词，表示现在，马上，此刻。

  You've got to ask him.It's now or never.

  你得去问他,机会难得。

  Until now she has never been to see a doctor.

  到目前为止她还没有去看过医生。

  二.now用作名词，表示现在，目前。

  The boss is being in royal spirits right now.

  此刻，老板情绪极好。

  Now he slept quietly with his fathers.

  此刻他安静地躺在祖坟中。

  三.now用作形容词，表示现在的，当今的。

  She had now a life filled also with a beneficent activity.

  她目前的生活里善行颇多。

  Now, a living language has been found that can play the same intermediary role more successfully.

  最近，已找到了一种现存的语言，它能更有效地起到中间媒介的作用。

  四.now在句中除作状语外,还可作主语、表语或介词宾语。