想要做某事的英语表达可以用以下句式：I want to do something. （我想要做某事。）I would like to do something. （我想要做某事。）I am interested in doing something. （我对做某事感兴趣。）I am eager to do something. （我渴望做某事。）I am keen to do something. （我热衷于做某事。）I am determined to do something. （我决心做某事。）其中，want to和would like to是表示“想要”、“愿意”的常用表达；interested in表示“感兴趣”；eager to表示“渴望”、“热望”；keen to表示“热衷于”；determined to表示“决心”。