Completing the design of the toy is really a happy thing ,but it remains ___ whether the toy will be welcomed by the public.A to seeB to be seen为什么这里要用被动啊?

Completing the design of the toy is really a happy thing ,but it remains ___ whether the toy will be welcomed by the public.A to seeB to be seen为什么这里要用被动啊?
Completing the design of the toy is really a happy thing ,but it remains ___ whether the toy will be welcomed by the public.
A to see
B to be seen
为什么这里要用被动啊?

Completing the design of the toy is really a happy thing ,but it remains ___ whether the toy will be welcomed by the public.A to seeB to be seen为什么这里要用被动啊?
因为主语是it 指物 所以只能是被看 所以选不定式的被动语态to be seen

因为it指代逗号前的整个句子的意思，这件事有待于人们进一步观察，see和这件事是被动关系，所以需要用to be seen。