Examples of Context Free Languages

I'm having a hard time thinking of context free languages. The only example I've been able to think of is $0^n1^n$, but I'm having a hard time thinking of any others. Can I get some examples?

Here are some of the examples of context free languages

• $\{ w \in \{0,1\}^*\mid \ w$ contains at least three ones }

• $\{ w \in \{0,1\}^*\mid \ w = w^{R}$ and $\mid w \mid $ is even }

• $\{ w \in \{0,1\}^*\mid \ $ the length of $w$ is odd and the middle symbol is $0$ }

• $\{ a^{i} b^{j} c^{k} \mid \ i,j,k \ge 0 $ and $ i + j = k $ }

• $\{ a^{i} b^{j} c^{k} \mid \ i,j,k \ge 0, $ and $ i = k $ or $i = k$ }

• $\phi$

Reference : https://web.njit.edu/~marvin/cs341/hw/hwsoln05.pdf

StackExchange Computer Science Q#71550, answer score: 4