now表明句子的时态应该是现在时态，包括现在进行时，一般现在时或现在完成时。now在句中的位置也比较灵活，句首，句中，句末都可以。
Well, I\'d better be going now.
就这样，我现在该走了。
The conflict has now reached a new level of intensity.
冲突现在已经达到了新的激烈程度。
Digital television has been around for some time now.
数字电视已经面市一段时间了。
