In the course of the week's run of "Romeo and Juliet" at the Kennedy Center, the London Festival Ballet introduced two more Juliets dancing opposite Rudolf Nureyev in his own production of the work. Curiously, the ballerinas appeared in reverse order, insofar as their impact on the role went.

Eva Evdokimova, who danced the opening last Tuesday, was decidedly the weakest. Patricia Ruanne, in her second performance Thursday evening, fared much better. Elisabetta Terabust, on Saturday evening, was better still.

If, on the whole, the performance with Ruanne was the most moving of the three, the reason was simple enough - her partnership with Nureyev seemed to click emotionally in a way the others did not. As Juliet she has shortcomings - tight, hunched shoulders, stiff arms and an overly emphatic attack, among them. But she compensated with a kind of dramatic intensity almost entirely missing from Evdokimova's performance, and a sense of tragic urgency.

Terabust's protrayal combined best features of her predecessors. She had the lyrical fluency that was Evdokimova's outstanding quality, buttressed by her own clarity of articulation. But she also had Ruanne's dramatic conviction, unmarred by the latter's stylistic flaws. Her transformation from girlish ebullience to womanly ardor and anguish was most persuasive. Still, for whatever reason, it was Ruanne who called forth the most responsive chords from Nureyev's Romeo.

Repeated viewings only served to confirm the conceptual strength of Nureyev's production. There are shortcomings, to be sure, including ensemble dances so packed with steps they're all but illegible; bedroom calisthenics for the lovers that are more ungainly than romantic or sensual: and a dull, lengthy sequence for Paris and his retainers that dangerously impairs the flow of the drama. But the tragic power and brooding inevitability Nureyev has achieved in his treatment of the ballet outweigh all else.

In general, the company danced with greater physical and dramatic assurance as the week proceeded. So did Nureyev himself, moreover, despite the wear and tear of his multiple appearances.