实际上 + Clause
实际上 (shíjìshang) means "actually," "in fact," or "in reality" and is used to reveal the truth behind an appearance or assumption. It typically appears at the beginning of a clause to introduce a correction or surprising fact. This adverb is common in both spoken and written Chinese.
他看起来很年轻,实际上已经四十岁了。
Tā kàn qǐlái hěn niánqīng, shíjì shang yǐjīng sìshí suì le.
He looks very young, but he's actually already forty years old.
这道题看着简单,实际上非常难。
Zhè dào tí kànzhe jiǎndān, shíjì shang fēicháng nán.
This problem looks simple, but it's actually very difficult.
实际上,我们早就认识了。
Shíjì shang, wǒmen zǎo jiù rènshi le.
Actually, we got to know each other a long time ago.