The workers were overcome by the intense heat in the workshop.

overcome 是动词，由前缀 over-（表示"超过、过度"）和动词 come（来）组成，字面意思是"超越而来"，引申为"战胜、克服"。在这里是被动语态 were overcome，表示"被...压倒/击倒"的意思。