郊游系列可以用英文表达为 "Outing Series" 或 "Picnic Series"。具体选择哪个短语取决于上下文和想要传达的语气。如果是在提到一系列的郊游活动，可以使用 "Outing Series"；如果是特指一系列关于野餐或户外活动的文章、书籍或节目，则可以使用 "Picnic Series"。以下是一些可能的写法：
Outing Series
Picnic Series
Outdoor Adventure Series
Nature Walk Series
Family Picnic Series
Weekend Getaway Series
Hiking Trip Series
Rural Retreat Series
Outdoor Activities Series
Summer Outing Series
