how to use flurl to get the response body with query string parameters - flurl

Question

how to use flurl to get the response body with query string parameters. I tried using Postman and the results were as I expected. but I can't apply it to flurl.
var strUrl = await "https://example.com/api/v2/xxx/yyy?need_personalize=true&promotionid=2007354722&sort_soldout=true"
.WithHeaders(new
{
user_agent = "Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36",
content_type = "application/json",
referer = "https://example.com/xxx",
cookie = myCookies
})
.PostJsonAsync(new
{
need_personalize = true,
promotionid = 2007354722,
sort_soldout = true
});
bodyUrl = await strUrl.GetStringAsync();
the results I got : 200
{
"version": "6f1e0da21b667876ba3853b59a8bb812",
"error_msg": null,
"error": 10010
}
the resulting response should be like this :
{
"version": "6f1e0da21b667876ba3853b59a8bb812",
"data": {
"selling_out_item_brief_list": [
{
"itemid": 466536326,
"from": null
}
],
"items": [],
"mega_sale_items": [],
"item_brief_list": [
{
"itemid": 6720842242,
"from": null,
"is_soldout": false
}
],
"promotionid": 2007354722
},
"error_msg": null,
"error": 0
}
maybe anyone can help me?