だれかがドアをこつこつとたたいている。
Sentence Analyzer
English Translation
        Someone is tapping at the door.
    
Furigana
        だれかがドアをこつこつとたたいている。
    
Romanji
        Dare ka ga doa o kotsukotsu to tataiteiru.
    
Words
            
                誰
            
            
                (だれ、たれ、た)
            
        
        
            who
        
    
            
                か
            
            
                (か)
            
        
        
            indicates a question (sometimes rhetorical); or; whether or not; some- (e.g. something, someone); indicates doubt, uncertainty, etc.; emphatic prefix; suffix forming adjectives or adverbs; in that way
        
    
            
                が
            
            
                (が)
            
        
        
            indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and
        
    
            
                ドア
            
            
                (ドア)
            
        
        
            door (Western-style)
        
    
            
                を
            
            
                (を)
            
        
        
            indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.
        
    
            
                こつこつ
            
            
                (こつこつ、コツコツ)
            
        
        
            unflaggingly; steadily; untiringly; laboriously; knocking; tapping; clicking; drumming
        
    
            
                と
            
            
                (と)
            
        
        
            if; when; and; with; particle used for quoting (with speech, thoughts, etc.); quoting particle; promoted pawn; indicates question (sentence end)
        
    
            
                叩く
            
            
                (たたく、はたく)
            
        
        
            to strike; to clap; to knock; to dust; to beat; to play drums; to abuse; to flame (e.g. on the Internet); to insult; to use up money; to call; to invoke (e.g. a function)