now是什么时态的关键词

　　We're used to the noise from the traffic now.

　　现在我们已经适应车辆往来的噪音了。

　　This unit is now an established part of the course.

　　这个单元现在为本课程既定的一部分。

　　There isn't nearly enough time to get there now.

　　现在根本没有足够的时间赶到那儿。

　　Now is a good time to invest in the property market.

　　现在是对房地产市场投资的好时机。

　　Now let me see ─ how old is she now?

　　让我想一想，她现在多大了呢？