Mandarin Chinese uses the morpheme ZAI in front of a verb to mark the progressive aspect, expressing an unbounded, ongoing event from a close proximity, as illustrated here:
他们在吃饭
tamen zai chi fan
they ZAI eat meal
‘They are eating a meal.’
The progressive marker zai precedes the verb and encodes a dynamic ongoing situation
as in the middle of happening, as shown below:
他们在打球
tamen zai da qiu (Activity)
they ZAI play ball
‘They are playing ball.’
张三在写一封信
Zhangsan zai xie yifeng xin (Accomplishment)
Zhangsan ZAI write one-CL letter
‘Zhangsan is writing a letter.’
