$\textit{1. In the 1970.}$

$\Rightarrow$ Dẫn chứng : "In the 1970, skateboarding suddenly....popular."

$\textit{2. They are 'freestyle', 'ramp' and 'street style' skateboarding.}$

$\Rightarrow$ Dẫn chứng : "At first, skateboarders......and ramp"

$\textit{3. It's a combination of freestyle and ramp.}$

$\Rightarrow$ Dẫn chứng : "This was.....and ramp"

$\textit{4. Because it helps them skateboard safely.}$

$\Rightarrow$ Dẫn chứng : "This allowed....safely."

$\textit{5. Yes, because it appears so much in street.}$