这是约翰着手开始粉刷房子。It is John who set about painting the house.
这是玛丽着手开始组织活动。It is Mary that set about organizing the event.
这是团队着手开始开发新产品。It is the team that set about developing the new product.
在这些例子中，强调的是发起或开始做某事（粉刷房子、组织活动、开发新产品）的人或团队（约翰、玛丽、团队）。"这是"用于引出句子的主语，接着是被强调的名词短语（约翰、玛丽、团队），然后是动词短语"着手开始做某事"。
In all these examples, the emphasis is on the person or group (John, Mary, the team) who initiated or started the action of doing something (painting the house, organizing the event, developing the new product). "It is" is used to introduce the subject of the sentence, followed by the emphasized noun phrase (John, Mary, the team) and then the verb phrase "set about doing (sth)".