Lingling said "Why don*t we go to one of our national park to relax" 改为间接引语

Lingling said "Why don*t we go to one of our national park to relax" 改为间接引语
Lingling suggested _________________________
老师说横线上填 Lingling suggested why they went to one of them national park to relax"
Lingling suggested that they go to one of them national park to relax"
我觉得是答案对,但老师说这个问句用why提问就要引用why.
疑惑,希望得到解决~