我认为原因之一就是他们的家庭太贫困，而无法供应他们上学。结构中的不定式可根据其是否及物来确定它是否带宾语。此时还需注意，该不定式通常也不用被动式，尽管意义上是被动的。但在某些特殊的语境，其中的不定式必须要用被动式。转换，但此时要注意把原句型中的形容词改为相对应的反义词。结构可以表示肯定意义，而不是否定意义：1.当不定式前有否定词修饰时。
27. Now in the rural areas, there are many children out of school. I think one of reasons is that their families are too poor to afford their schooling.
现今，在农村地区还有很多孩子失学。我认为原因之一就是他们的家庭太贫困，而无法供应他们上学。
解析：
经典句型too…to句型解析
一、基本结构特点
too…to…结构的基本形式为“too 形容词或副词 to 动词原形”，其意为“太……以至于不能……”，“太……而不能”；如：
She is too young to know right from wrong.
她太小了，还分不清是非。
He is too shy to speak to her. 他太害羞，不敢同她讲话。
It’s too cheap to be good. 这东西太便宜，好不了(即便宜无好货)。
He is too young to know right from wrong. 他太小，还分不清是非。
My sister is too young to attend school.
我妹妹年纪太小没法上学。
She’s too mean to make a donation. 她很小气，不肯捐款。
You're too young to be contemplating retirement. 《牛津高阶英汉双解词典》
你考虑退休还太年轻。
Now I’m too busy to discuss it with you. 我现在太忙，没时间和你讨论。
But these were only daydreams, much too heavenly to be contemplated as real possibilities.
但是，这些愿望都只是白日做梦，因为它们太美妙了，简直叫人不敢相信真的会实现。《密西西比河上的生活》
二、不定式的逻辑主语
有时不定式前可以带有一个由介词for引出的逻辑主语。如：
It’s too expensive for her to buy. 太贵了，她买不起。
The box is too heavy for the boy to carry. 这个箱子太重，这男孩提不起。
The print is too small for me to read without glasses. 印刷字体太小，我不戴眼镜就看不清。
三、不定式是否带宾语
在通常情况下，too…to…结构中的不定式可根据其是否及物来确定它是否带宾语。如：
He is too tired to go any further. 他太累了，不能再往前走了。(不定式to go不及物，无需带宾语)
She is too poor to buy such a nice a dress. 她太穷，买不起那件漂亮的连衣裙。(不定式to buy后带有宾语 such a nice a dress)
但是，若句子主语与其后不定式有动宾关系，那么，其后的及物动词不定式不能带宾语。如：
The nice dress is too expensive for her to buy. 这件漂亮的连衣裙太贵了，她买不起。(to buy在此虽为及物动词，但由于句子主语the nice dress与该不定式to buy有动宾关系，故to buy后不宜再接代词it作宾语)
注意：若句子主语与其后不定式有动宾关系，且其中的动词为不及物动词，此时应注意在其后加适当的介词。如：
The room is too dirty to live in. 这房间太脏，不能住。(句末的介词in不可省略)
四、不定式是否用被动语态
上面讲到，若句子主语与其后不定式有动宾关系，其后作为及物动词的不定式不再带宾语。此时还需注意，该不定式通常也不用被动式，尽管意义上是被动的。如：
The text is too difficult to understand. 这课文太难了，理解不了。
The text is too difficult for the students to understand. 这课文太难了，学生理解不了。
但在某些特殊的语境，其中的不定式必须要用被动式。如：
He spoke in a voice too low to be heard. 他说话的声音太低，听不见。
He is too young to be sent to America for advanced study. 他太年轻，不能送到美国去深造。
主语是不定式动作的承受者时，不定式既可以时主动也可以说被动：
The milk is too hot to drink.= The milk is too hot to be drunk.牛奶太贪了，喝不了。
The box is too heavy to carry. = The box is too heavy to be carried.箱子太重，搬不起来。
Atoms are too small to see. = Atoms are too small to be seen.原子太小，看不见。
五、与so [such]…that结构的转换
1. The box is too heavy for me to carry.
→The box is so heavy that I can’t carry it.箱子太重，我扛不动。
→It is such a heavy box that I can’t carry it.
2. The child is too young to dress himself.
→The child is so young that he can’t dress himself.
→He is such a young child that he can’t dress himself.
注：有时还可与 not…enough to…转换，但此时要注意把原句型中的形容词改为相对应的反义词。如：
The child is too young to dress himself.
→The child is not old enough to dress himself.
孩子太小，不会自己穿衣。
He’s so young that he can’t take care of himself.
He isn’t old enough to take care of himself.
He’s too young to take care of himself.
他太小了，照顾不了自己。
六、too…to…有时可表示肯定意义
在以下几种情况，too…to…结构可以表示肯定意义，而不是否定意义：
1. 当不定式前有否定词修饰时。比较：
He is too foolish to understand this. 他太蠢，不会明白这一点。
He is too clever not to understand this. 他太聪明，不会不明白这一点。
She was too kind not to help you.她很善良，不会不帮助你。
Alicy is too careful not to forget it.
爱丽丝非常细心，不会忘记这件事的。
2. 当副词too的前面有否定词修饰时。如：
It’s never too late to mend.改过不嫌晚。
Never too old to learn. 活到老学到老。
It’s never too late to stop smoking. 戒烟何时都不算晚。(直译：永远不会太迟而不能戒烟)
English is not too difficult to learn. 英语并不太难学。
3.如果too后面的形容词表示主语的状态、心理活动、情感态度（常见的有glad, easy, ready, anxious, eager, willing, happy、pleased，apt, satisfied, inclined,kind等），并与其后的不定式构成固定搭配，这时too含有肯定意义，表示“very, extremely”的意思。例句：
We are only too happy to take care of your dog for the weekend.
我们非常乐意周末帮你照顾狗狗。
Mr.Smith was too eager to see her.
史密斯先生极想见到她。
I’m only too glad to be of help. 我非常乐意帮忙。
Everyone here is too ready to help others. 这里人们都很乐意帮助他人。
I'm too anxious to know the result.
我极想知道结果。
I’m too glad to see you again. 又见到你我很高兴。
We are too ready to help you. 我们很乐意帮助你。
I shall be only too pleased to get home. 我要回到家里就非常高兴。
注：这类句子中的too通常含有very之意，且too前通常会有only, just等副词修饰。
当too前面有only、all、but、quite修饰时，意思时非常，等于very，表示肯定：
I’m only pleased to be able to help you.我非常高兴能帮助你。
I'd be only too glad to help.
我非常愿意帮忙。
I was only too glad to help him if he asked.
如果他提出来，我乐得帮助他。
I was only too pleased to help.
我非常乐意帮忙。
We're only too pleased to help.
我们非常愿意帮忙。
When the new baby comes along it is only too easy to shut out the others.
新生儿出世后，其他孩子极容易受到冷落。
The Conservative Government was only too quick to hush him up.
保守党政府很快就堵住了他的嘴。
I'll be only too pleased to help them out with any queries.
我非常乐意为他们答疑解惑。
He was but too eager to get home.他非常想回家。
We were all too polite to object.
我们都太客气了，没有反对。
《牛津高阶英汉双解词典》
It was all too easy to believe it.
这太容易令人相信了。
《柯林斯高阶英汉双解学习词典》
Teenagers occasionally find it all too much to cope with and lapse into bad behaviour.
青少年偶尔会因感到压力太大无所适从而做出不良行为。
It is all too easy to lose sight of what is happening on our own doorstep
我们很容易无视身边之事。
