Context-free grammar for $L=\{0^n1^{2n} \mid n \geq 0\}$ How can I express this language $L = \{0^n 1^{2n} \mid n ≥ 0\}$ as a context-free grammar?

I am new to this field and I am not sure what should I do. Please help me.
As Yuval commented, this is a very basic exercise so you should probably go over the basic definitions. One simple answer for this particular question is:
$$S\rightarrow0S11|\varepsilon$$