Dưới đây là những từ phù hợp để điền vào chỗ trống:

(1) **dish**
(2) **introduction**
(3) **when**
(4) **easy**
(5) **special**

Vậy đoạn văn hoàn chỉnh sẽ là:

"This (1) **dish** is called "nem ran" by northerners and "cha gio" by southerners. In Ha Noi, the (2) **introduction** of "nem ran" dates back to a time (3) **when** "cha ca" had not existed. Although it ranks among Vietnam's speciality dishes, "nem ran" is very (4) **easy** to prepare. Consequently, it has long been preferred food on (5) **special** occasions such as Tet and other family festivities."