will当助动词和情态动词时的用法 百科上说will既可以当助动词又可以当情态动词.请问当助动词时时哪种情况?可是,我查大辞典,will都是当情态动词讲,没有助动词的解释.这是为什么呢?

will当助动词时,无实意,后加动词原形构成将来时.结构是：主+will+do+宾.
它不随主语变化而变化,在助动词中,它只有will一种形式.
字典里没有关于情态动词的解释是因为它当情态动词讲是用它的过去式 would.
will当情态动词时,只用它的过去式would来使用,译为“愿意”.结构为：would+主+like+to+do+宾.
固定搭配为：Would you like to ---.译为 你愿意做---吗?表情求,同样不随主语变化而变化.
关于would,看看这个你会更明白：
would
[wud, wəd, əd, d]
v.
aux. (will 的过去式)
[表示过去将来时, 用于第二、三人称](第一人称英国用 should, 美国用 would) 将, 会
He said he would come.
他说他要来.
[表示意愿]愿; 偏要, 肯
He would eat nothing.
他不肯吃东西; 他什么也不愿吃.
I told him not to go, but he would not listen.
我叫他别去, 可他偏不听 .
He would go in spite of our warnings.
他不听我们的劝告, 执意要去.
[表示过去的习惯动作]常常, 总是
He would sit for hours doing nothing.
过去他常常 坐几个钟头什么事也不做.
He would come to see us on Sundays.
过去星期天他经常来看望我们.
[表示推测]大概, 该是
I would be about ten when my brother left home.
我哥哥离开家时, 我大概十岁左右 .
[表示某种假设的意志]想要, 愿意
I could do so if I would.
要是我愿意, 我能够这样做(但我不愿意).
If you would do this for me, I should be grateful indeed.
若是你愿意为我做这件事, 我将万分感激 .
[表示虚拟, 假设, 虚 构, 用于虚拟条件句的主句第二、第三人称, 美国也用于第一人称]要, 会, 就会, 将要
They would be killed if the car went over the cliff.
如果汽车翻在悬崖下, 他们就会丧命.
They would have been killed if the car had gone over the cliff.
如果汽车当时翻到悬崖下, 他们早就丧命了.
[表示请求或个人想法、看法, 使语气更婉转]请
Would you kindly show me the way to the station?
劳驾, 请问到车站的路怎么走?
I would like to speak a few words.
我想讲几句话.
It would seem that he was right.
看来他倒是对的.
[表示假想的愿望]但愿, 要是...多好
Would [I would] that they were safe home again!
愿他们再能平安回家 !
Would that I were young again.
我若能再年青些该多好啊!
We wish that he would come again.
我们但愿他会再来 .
I would rather you came on Sunday.
希望你星期天来 .
[表示能力](=could) 能
The barrel would hold 100 litres.
这桶能装一百升 .
习惯用语
wouldrather [sooner]...than
宁愿, 宁可...也不
wouldrather do sth.
倒更希望, 更喜欢