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The more I think of them,the more questions I think of to ask.
the more questions I think 中,the more questions是先行词
原句应该是the more questions （that）I think of to ask.
因为that是做I think of 的宾语,所以可以省略.
the more questions I think of其实已经完整
to ask表示目的,“去问”
原句：我想得越多,我越有问题想去问.