He is too young to understand it.

他太小了，还不懂这个。

同一单元的其他句子

• Have you read Treasure Island yet?你读过《金银岛》了吗？
• I haven't finished the book yet.我还没读完这本书。
• She has already read it twice.她已经读了两遍了。
• We are going to read it next week.我们下周打算读它。
• He has just started reading it.他刚开始读。