Chinese aspect-markers like 了、过 and 着 show the temporal relation an event has to the time-period you are talking about. However, unlike tense-marking on English verbs, where we obligatorily mark each verb with the appropriate tense (-ed, -t, -en, -ing etc.), Chinese has a tendency to ONLY put aspect-markers after the MAIN verb of the sentence – regardless of their ‘tense’. English-speakers learning Chinese thus need to be very careful about WHICH verb they put words like 了、过 and 着 words after. Some ‘rules of thumb’ of the kinds of verbs that usually won’t take an aspect marker include:
* auxiliary verbs
我当时想了见到他。 WRONG
我当时想见到他。 RIGHT
‘At that time, I wanted to see him.’
* prepositions / coverbs
我帮了你买车票。 WRONG
我帮你买了车票。 RIGHT
‘I bought you a train ticket
(literally: I helped you by buying your train ticket for you).’
* pivotal verbs e.g. causatives
妈妈昨天让了我早点去上课。 WRONG
妈妈昨天让我早点去上课了。 RIGHT
‘My mum made me go to class early yesterday.’
* verbs of reporting
他说了他不要我参加。 WRONG
他说他不要我参加。 RIGHT
‘He said he didn’t want me to participate.’
Of the various errors I’ve seen in choosing which verb to aspect-mark, the most common is made when using 来 and 去 before a verb and marking the 来 / 去, rather than the MAIN verb that conveys the meaning of the sentence. In such sentences, 来 and 去 are purely acting as ‘helping verbs’ and so you should not mark them with 了, 过 etc. (even when talking about the past). Compare:
你去过那里吃饭没有？ WRONG
你去那里吃过饭没有？ RIGHT
‘Have you been there to eat (before)?’
大卫生病的时候就来了我家睡了几个小时觉。 WRONG
大卫生病的时候就来我家睡了几个小时觉。 RIGHT
‘When David was sick, he came to my house to sleep for a few hours.’
中文秘诀 | The Secret of Chinese 