toss a coin

详细解释:掷钱币猜其落地时是正面还是反面

例句：

It was fifty-fifty chance which staircase he would use. So I tossed a coin and waited hopefully at the exit.难说他将从哪道楼梯下来。于是，我抛币而定，并满怀希望地等候在出口处。