Mixing Chinese and English in this kind of situation is pretty normal. If someone has been abroad for a long time, or if their job is with a foreign company, then mixing Chinese and English is very common. So what kind of Chinese-English mixing is considered normal? For example, certain professional terms—like some commonly used, very natural-sounding words—using English is totally normal. In my own work, I use some professional terms in Chinese and they can feel awkward to say, so during business communication, it’s easy to switch to Chinese and English.