摩托车手必须戴头盔以作保护。

Motorcyclists are required to wear a ___helmet for protection.

骑自行车时戴头盔很重要。

It's important to wear a ___helmet when riding a bicycle.

为了安全骑行，准备一辆好自行车、头盔和防护服。

Get a good bicycle, a ___helmet, and protective clothing for safe cycling.