他明明知道这个问题很难。
tā míngmíng zhīdào zhègè wèntí hěn nán 。
He obviously knows that this problem is very difficult.
你明明说过你会来。
nǐ míngmíng shuō guò nǐhuì lái 。
You definitely said that you would come.
明明是错误的，为什么你还坚持？
míngmíngshì cuòwù de ， wéishènmǒ nǐ huán jiānchí ？
It is obviously wrong, why do you still insist?