This is about three weeks old, as you can see growing like a weed.

这是大约三周大的，你可以看到它像野草一样生长。

He just turned 16 and is growing like a weed. He's taller than I am now! And he's so smart.

他刚满16岁，长得特别快。他现在比我高啦！他也很聪明。

I don't know if you've noticed this, but sometimes kids go through a growth spurt, and we use the phrase to grow like a weed to describe this change.

我不知道你是否注意到这一点，但有时孩子会经历一个生长突增期，我们用“像野草一样生长”这个词来形容这种变化。