一、He is too young to go to school.
他年纪太小了，不能去上学。
二、He is so young that he can't go to school.
他年纪太小了以至于不能去上学。
三、He is not old enough to go to school.
他年纪不够，不能去上学。
这里共用了三种固定短语的表达方式：
1、too……to……太怎么样以至于不能怎么样
例句：
He's too old to go to work.
他年纪太大了以至于不能去工作。
He's too full to continue eating.
他吃的太饱了以至于不能继续吃下去。
2、so……that……
如此……以至于
例句：
He's so fat that he couldn't run.
他太胖了以至于不能跑步。
He's so happy that he forget the time.
他太开心了以至于忘了时间。
3、no……enough to……
不够……去做某事
例句：
He's not confident enough to deliver a speech.
他不够自信去演讲。
He's not brave enough to feed the tigers.
他不够勇敢去喂那些狮子。
扩展资料：
so that 是一种结果状语从句，结果状语从句是英语学科中的一个句型。从句常由so… that或such…that引导。掌握这两个句型，首先要了解so 和 such与其后的词的搭配规律。
结果状语从句的从句部分是补充说明主句中谓语动词发生的结果的，通常位于主句之后。结果从句中通常不用情态助动词，但must,can,could除外。
such用在（形容词）名词之前；而so要用在形容词/副词之前，so或that有时会省略掉。以下逐一介绍高考中常见的引导结果状语从句的词：so that可以引导目的状语从句， 也可以引导结果状语从句。
例如：
He worried so that he couldn’t sleep.
他急得睡不着。(so that引导结果状语从句)
It was very cold, so that the river froze.
天气寒冷， 河水都结冰了。(so that引导结果状语从句)
I came to the class early so that I could see the classmate beside me.
我赶早来上课， 以便早点看到我旁边的同学。(so that引导目的状语从句)
so+形容词+that
Some people were so moved by the sight that they began to cry.
一些人对此情景如此感动，以致开始哭了出来。
The wind was so strong that he could hardly move forward.
风刮得如此猛烈，以致他几乎是寸步难行。
so+副词+that
The ball struck him so hard that he nearly fell into the water.
球重重地打在了他身上，使他几乎落到水里去。
so+形容词+a+单数名词+that
It was so hot a day that they wanted to go swimming.
天那么热，他们想去游泳。
so+many/few（+复数名词）+that
There are so many picture-story books that the boy won't leave.
有那么多连环画书，小孩都不想离开了。
so+much/little+单数不可数名词）+that
There is so much contradictory advice about exercising that you become confused.
对于锻炼有那么多互相矛盾的意见，以致都把你给弄糊涂了。
He gave me so little time that it was impossible for me to finish the work on time.
他给我的时间如此少，要我按时完成任务是不可能的。
参考资料：百度百科-结果状语从句