so they decided to have a picnic by the _____(填什么)

so they decided to have a picnic by the _____(填什么)
so they decided to have a picnic by the _____(填什么)

so they decided to have a picnic by the _____(填什么)
lake.他们决定在湖边野餐.

weekend

这个问题回答最好要有前后文，不过picnic通常和地点有连接，例如：have a picnic in a park, in the rain, in your mate's house and in a pub.
have a picnic on mountainside.等等。
因此前面两个回答，如果让我选，我选by the lake(在湖边）