\(\left\{ \begin{array}{l}x = t\\y = t\\z = t\end{array} \right.\left( {t \in \mathbb{R}} \right)\)

\(\left\{ \begin{array}{l}x = t\\y = 0\\z = 0\end{array} \right.\left( {t \in \mathbb{R}} \right)\)      

\(\left\{ \begin{array}{l}x = t\\y = t\\z = 0\end{array} \right.\left( {t \in \mathbb{R}} \right)\)      

\(\left\{ \begin{array}{l}x = 0\\y = 0\\z = t\end{array} \right.\left( {t \in \mathbb{R}} \right)\)