打消这种幼稚的念头吧。

Get rid of those kinds of naive ideas.

Source: Tatoeba

of; ~'s (possessive particle)
(used after an attribute when it modifies a noun)
(used at the end of a declarative sentence for emphasis)
(used after a noun, verb or adjective to form a nominal expression, as in 皮革的 pígéde "one made of leather" or 跑堂儿的 pǎotángrde "a waiter (literally, one who runs back and forth in a restaurant)" or 新的 xīnde "new one")
also pr. dì or di in poetry and songs