triplet [lens]

例句：

1. 1. The triplets are the only children in their family.
   这对三胞胎是他们家唯一的孩子。
2. 2.The triplets were born on the same day and have the same birthday.
   这对三胞胎在同一天出生，生日相同。
3. 3.Triplets are often more difficult to raise than singletons.
   三胞胎通常比单胞胎更难抚养。