Do all the $7$-cycles in $S_7$ generate $S_7$? How?
Can we generalize the idea?
(Edited)
I found a new idea:
Assume $$\sigma = (x_1,x_2,x_3,x_4,x_5,x_6,x_7)$$ and $$\tau=(x_7,x_6,x_5,x_4,x_3,x_1,x_2)$$ Now: $$\sigma\tau=(x_1,x_2,x_3)$$ So, we can generate all $3$-cycles.
Theorem: Let $n ≥ 3$. Prove that $A_n$ can be generated by all the $3$-cycles in $S_n$.
What should I do for $S_n - A_n$?
Thank you for your answers.
No. A $7-$cycle has parity $+1$, therefore you cannot reach a transposition just using $7-$cycles.