be useful to sb【例句】He might be useful to us. 我们也许用得上她。（摘自《牛津高阶英汉双解词典》第9版）information which will be useful to new mothers 会对新手妈妈有帮助的信息 （摘自《牛津英语搭配词典》第2版）  

   be useful to do 是什么意思，有这样的用法吗？【例句】It can be useful to write a short summary of your argument first. 先把你的论点纲要写下来可能会有帮助。（摘自《牛津高阶英汉双解词典》第9版）

    be useful for sth./ for doing sth  【例句】These plants are particulare useful for brightening up shady areas. 这些植物特别有助于让背阴的地方明亮起来。（摘自《牛津高阶英汉双解词典》第9版）/ This tool is useful for a variety of purposes. 这个工具是多用途的。（摘自《牛津英语搭配词典》第2版）/ Intenet booking is useful for people who want a short break. 网上预订对需要短期度假的人有用。（摘自《牛津英语搭配词典》第2版）    

    be  useful in sth 在......方面擅长；be useful in doing 是“擅长于做某事”，【例句】She was very useful in dealing with foreign visitors . 她很善于同外国访客打交道。（摘自《牛津英语搭配词典》第2版）