赤子之心的英文：
1.utter innocence

参考例句：

The innocent heart of a child
赤子之心

I have the pure heart of a newborn baby.
我有一颗赤子之心。

utter是什么意思：
v. 以口发出声音；说
adj. 彻底的；完全的

You scatter its uttering.
你散播其话语。

utter(a sound)with voice
发（浊音）

How can you utter such falsehoods?
你怎么能说出这种谎言？

A low grumble or indistinct utterance.
咕哝低声地嘟哝或者不清楚地说话

The battlefield was a scene of utter carnage.
战场完全是一片大屠杀的惨象。

innocence是什么意思：
n. 清白；天真无邪；无知，幼稚

Innocence is bliss.
无知便是福。

Satisfy the police that one is innocent/as to one's innocence.
向警方证实自己是清白的。

She was wearing an innocent smile.
她带着天真的笑容。

It is a scandal that the defendant was declared innocent.
宣判被告无罪，这真是可耻的事。

He tricked that innocent girl.
他欺骗了那个纯真的女孩。