你可以说 "They are all wearing helmets"。这句话的来源是英语中动词 "wear" 的过去式，表示某人正在戴着某物。"Helmet" 是指头盔。
下面是一些例句：
"They are all wearing helmets to protect their heads while biking."（他们都戴头盔保护他们骑自行车时的头部。）
"I always wear a helmet when I'm riding my motorcycle."（我骑摩托车时总是戴头盔。）
"It's a safety requirement to wear a helmet on construction sites."（在建筑工地上必须戴头盔是安全要求。）
下面是一些例句：
"They are all wearing helmets to protect their heads while biking."（他们都戴头盔保护他们骑自行车时的头部。）
"I always wear a helmet when I'm riding my motorcycle."（我骑摩托车时总是戴头盔。）
"It's a safety requirement to wear a helmet on construction sites."（在建筑工地上必须戴头盔是安全要求。）