now是什么时态的标志词?(now时态判断方法)

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作副词表示“现在、目前、此刻、从现在开始、表示厌烦”；作连词表示“既然、由于”。在句中的位置也比较灵活，句首，句中，句末都可以。

justnow用于可用于现在时或将来时。justnow作“刚才”、“一会儿之前”的意思时，常与一般过去时连用，位于句首或句末；它也可指“（加重语气的）现在”或“片刻之后”。justnow如果用于过去式,意为“刚才”，just一般不用于否定形式。

up to now 意思是到现在为止,故用现在完成时。up to now 英[p tu: nau] 美[p tu na] adv. 至今; 迄今; 到目前为止; [例句]This is an attempt to put flesh on what has been a very bare skeleton plan up to now.害常愤端莅得缝全俯户这是一次试图使至今还只是框架的计划充实起来的尝试。

nowadays ：adv. 现今，现在，在句子中常用一般现在时：News flies about rapidly nowadays. 现在消息传播很快。《21世纪大英汉词典》He is a good player, as players go nowadays. 照目前一般水平而言，他是个好讥旦罐秆忒飞闺时酣江选手。《21世纪大英汉词典》He never tells me anything nowadays. 现在他什么也不告诉我了。

Let‘s see if the baseball game has started yet.Started?It must be clear who ( ) by now.A: is winning B:wins C:has won D:would win
这题选A: is winning原句还原是：It must be clear to find out who is winning at the moment（by now）by now 可用于多种时态，要根据语境具体分析哦。提供例句供亲参考。O(∩_∩)O~By now the power of the Roman Empire was on the wane. 到这时，罗马帝国已日益衰败。By now, putting satellites in orbit is old hat to space scientists. 现在，对航天科学家来说，把卫星送入轨道已不是一桩新鲜事了。By now she is redoing problems — how do I get characters into a room — dozens and dozens of times.到目前为止，她正在无数次地重复解决问题，我该怎么把一个个字母填入一个空位。By now, all good designers and developers realize the importance of usability for their work.现在，比较牛的设计师和开发者都认识到了可用性在他们工作中的重要性。Oh, and they go to Buckingham Palace to receive medals from the Queen and, by now, more or less accept it as their due.对了，他们还去了白金汉宫接受了女王的勋章，并且直到现在，或多或少地还是人们接受他们的原因。——————————————————-如对回答满意，望采纳。如不明白，可以追问。祝学习进步！O(∩_∩)O~

英语时态（括号内单词正确形式填空）1, — Do you know when Peter___( come ) from abroad. — Perhaps it will be a long time before he _____ ( come ).2, My uncle said that he would telephone me but I _____ ( not hear ) from him so far.
四十年前，山东战乱，张齐人怀有身孕的妻子被贼兵掳去。自己流落河南，重新安家娶妻，生子张讷，不久妻子去世，继娶牛氏，生子张诚。张讷遭继母牛氏虐待，起早贪黑干活，而张诚则对他关怀备至，常背着父母帮他砍柴。