昨天李教授反复思考了这一问题，直至想出令人满意的解决办法。
Yesterday Professor Li kept thinking over the problem until he came up with a satisfactory solution.
昨天李教授反复思考了这一问题，直至想出令人满意的解决办法。
Yesterday Professor Li kept thinking over the problem until he came up with a satisfactory solution.
