They were given two choices: they could either eat it or, if they waited fifteen minutes, they'd be given a second one (and then they could eat both) .
他们有两个选择:要么吃,要么等15分钟,再吃第二个(然后他们可以同时吃两个)。
2
70% ate the first marshmallow within fifteen minutes, but the other 30% showed willpower—they didn't eat the first one and waited for the second marshmallow quietly.