弄清的英文：
to clarify
to fully understand

参考例句：

I am going to ascertain the truth.
我将弄清事实真象。

Pearl's inevitable tendency to hover about the enigma of the scarlet letter seemed an innate quality of her being.
珠儿一味纠缠着要弄清红字之谜,看来是她的一种内在的天性。

However, the dyer's primary interest is in the relationships between the nature and the quantity of the dye used
但染色工艺家的主要兴趣，在于弄清所有染料的性质和剂量与最终产品颜色之间的关系。

It is difficult to comprehend the magnitude of his crime.
弄清他罪恶的大小是困难的。

They want to find out the cause and effect of the incident.
他们要弄清事件的来龙去脉。

It is difficult for me to see into his full meaning.
我很难弄清他的全部意思。

Elucidate a problem,mystery
阐明一问题、弄清一奥秘

I' m sorry, I can' t quite catch the drift of what you' re saying
很抱歉,我没能弄清你说话的意思。

a fact - finding panel
为弄清真相对民众作抽样调查

Find out how much your surveyor's and solicitor's fees will be.
弄清你要向鉴定员和律师支付多少费用。

clarify是什么意思：
v. 澄清；阐明；净化；清醒

His mind suddenly clarified.
他的头脑突然清醒起来。

I want to clarify matters.
我想要先澄清一下。

clarified butter used in Indian cookery.
纯净的黄油，用在印度烹调术中。

fully是什么意思：
adv. 完全地

My time is fully engaged.
我的时间完全被占用了。

This fully demonstrates their willingness to cooperate.
这充分表明他们愿意合作。

The bear was a fully grown adult.
那只熊已完全发育成熟。

understand是什么意思：
v. 懂，理解；了解，认识到；体谅

If you were older you might understand.
假如你年龄再大一点，你就会理解了。

I understand that skepticism.
我明白这一怀疑论。

You have to understand how cells interact.
你必须明白细胞是怎样相互作用的。