The phrase "on knees" can be replaced by a plethora of synonyms, depending on the context. In a religious or spiritual context, options include "praying," "worshipping," "revering," or "meditating." In a romantic or intimate context, examples might include "begging," "pleading," "proposing," or "worshipping." For physical tasks or labor, synonyms could be "scrubbing," "cleaning," "gardening," or "repairing." In a submissive or vulnerable context, synonyms could be "surrendering," "yielding," "submitting," or "groveling." In any case, there are numerous options for expressing the act of being "on knees," and the appropriate synonym will depend on the tone, context, and intended meaning of the sentence.