1. A speech translation apparatus comprising: an acquisition unit configured to acquire speech in a first language as a speech signal; a speech recognition unit configured to successively perform speech recognition on the speech signal to obtain a first language word string which is a result of the speech recognition; a translation unit configured to translate the first language word string into a second language to obtain a second language word string which is a result of translation; a search unit configured to search for at least one similar example for each first language word string, and, if there is the similar example, to acquire the similar example and a translation example which is a result of the translation of the similar example in the second language, the similar example indicating a word string that is similar to the first language word string in the first language; a selection unit configured to select, in accordance with a user instruction, at least one of the first language word string associated with the similar example and the second language word string associated with the translation example, as a selected word string; and a presentation unit configured to present one or more similar examples and one or more translation examples associated with the selected word string.