题目

已知一个布袋里装有4个红球、3个白球和a个黄球，这些球除颜色外其余都相同．若从该布袋里任意摸出1个球，摸红球的概率为，则a等于          答案：  5 －Come on in, Peter, I want to show you something. －Oh, how nice of you! I _____you _____to bring me a gift. [　　] A． never think, are going　　B． never thought, were going C． didn't think, were going　D． hadn't thought, were going