Answer by  
                                                                                          palaeologus (564)
                                                            
                          
                          
                                                          If a dependent clause of a sentence clearly takes place in the same time (past, present, future) as the main clause, the two verbs should be in the same time.
 
 "It rained when I come home." -- verb tenses disagree.
 "It rains when I come home." -- proper.
 "It rained when I came home." -- proper.