If somethingtipsthebalanceortipsthescales, it is the thing thatcausesaparticularsituationtohappenor aparticulardecisionto be made, when othersituationsordecisionsarepossible:
打破平衡局面；起决定性作用Theteamswereevenlymatcheduntil twoquickgoalsfrom RooneytippedthebalanceinfavourofEngland.两队本来势均力敌，直到鲁尼很快攻入两球，形势开始变得对英格兰队有利。
She was a goodcandidate, but herlackofcomputerskillstippedthescalesagainsther.她本来是个不错的候选人，但她缺乏计算机技能，这对她很不利。