Here's the answer:
“晚安”
(wǎn-ān)
Watch a real native speaker say it:
Here's how it sounds in a textbook:
Fun fact: the hundreds of thousands of people learning Chinese with Memrise get this phrase correct 95.52% of the time!
(wǎn-ān)
Fun fact: the hundreds of thousands of people learning Chinese with Memrise get this phrase correct 95.52% of the time!