他们正在骑自行车英语怎么说怎么写

他们正在骑自行车英语可以说是 "They are riding bicycles." 或 "They are on their bikes."
这种表达方式来源于英语中的动词 "ride" 和名词 "bicycle" 或 "bike" 的组合。
例句1:
"They are riding bicycles through the park." (他们正在公园里骑自行车)
例句2:
"I saw them on their bikes heading to the beach." (我看到他们骑着自行车去海滩)