before doing sth还是do sth

before doing sth还是do sth before sb doing还是do sth如题``` help,open的过去分词是什么?是before sb do sth.还是before sb doing sth... before doing sth 和 before you do sth,为什么? plan+to do sth.还是doing sth.还是 do sth. after do sth.还是after doing sth. promise doing sth还是to do sth mind doing sth还是 to do sth have somebody do sth 还是doing sth? finish to do sth还是doing sth why not do sth 还是doing sth enough doing sth 还是 to do sth never doing sth 还是do sth? expect to do sth还是doing sth? important do sth 还是,important doing sth use sth doing sth还是use sth to do sth got an invitation to do sth 还是 on doing sth/in doing sth/of doing sth have nothing to do but do sth还是doing sth