It is compulsory for the tourists to learn about the vital eco-systems before arriving.
Tourists are free to learn about the vital eco-systems before arriving.It is optional for tourists to learn about the vital eco-systems before arriving.Tourists are not required to learn about the vital eco-systems before arriving.Tourists are required to learn about the vital eco-systems before arriving.Hướng dẫn giải:Be required to V = được yêu cầu làm gì
Dịch: Khách du lịch bắt buộc phải tìm hiểu về các hệ sinh thái quan trọng trước khi đến.
