1. A sentence forming apparatus comprising: first storage means for storing in a correlated manner with each other a plurality of indexes in a first language, a plurality of words in the first language semantically in coordination respectively with said indexes and grammatical information relating to said respective words, the grammatical information being semantically restricted; selection menu forming means for forming a selection menu in the first language by utilizing the contents of said first storage means; input means for inputting selective information required for forming a sentence in response to said selection menu; second storage means for storing said inputted selective information; third storage means for storing syntax information relating to grammatical syntax of the first language and word information relating to words in the first language; first sentence assembly means for assembling a sentence in the first language utilizing said selective information and said syntax information and said word information in the first language; fourth storage means for storing syntax information relating to grammatical syntax of at least one second language and word information relating to words in the at least one second language; second sentence assembly means for assembling a sentence in the at least one second language semantically equivalent to said sentence in the first language utilizing said selective information and said syntax information and said word information in the at least one second language; and output means for outputting said selection menu, said sentence assembled by said first sentence assembly means and said sentence assembled by said second assembly means.