Firstly, ‘le’ in Chinese does not necessarily resembles a past, or even a perfect aspect. Both aspects could happen and the time of occurrence of an event is contextually based. It is true though to say that if something actualizes in time, then it is normally in the past to make sure that it has happened.
Secondly, le’ can be placed after a verb, not always at the end of the sentence, to indicate the actualization of an event in a time frame (Liu, 2015). For instance, in the Chinese sentence他學會了中文, ‘le’ is used to indicate that the state of ‘mastering Chinese’ has been realized (Liu, 2015). It can even combine with a sentence-final le to become 他學會了中文了 to assert the whole ‘new’ VP “學會了中文”.
So, a possible solution to solve the problem is to learn different uses of “le” and the corresponding situations that should be applied to. “le” is a protean particle which could have many kinds of use (Zhu, 2019). The usage here is to use “le” as an aspect marker which belongs to the category of aspectual particles (動態助詞). Since there are no verbs to indicate tenses in Chinese, “le” is shown in completed actions, placed between a verb and an object or between a verb and its complement (Zhu, 2019). For instance, “我洗了澡”, “le” is positioned between a verb and an object which stated that the action is completed (“I have showered”).
In fact, there are many more situations which the marker “le” can be used in Mandarin. Another situation is to put “le” at the end of the sentence, but also after an adjective. This is the basic use of “le” in specific set structures but not used for only “actions in the past”. It is used to strengthen the adjectives used beforehand. There are several common patterns for these “le” set structures: “太 [adjective]了; 可 [adjective]了; [adjective] 極了. The Chinese characters ‘太’, ‘可’, ‘極’ adjusts the degree of the adjectives. For ‘太’ and ‘極’, “le” is used to indicate a high representative degree, for example: “這件衣服太難看了” or “這件衣服難看極了”; for ‘可’, “le” is used to emphasise ‘very’, such as “他可開心了” and “他可懶了”. (OCLCE, 2008)
The change of state is another usage of “le”. It can be used to express different states, from now, the past to the future. It is also referred as a kind of transformative aspect. ‘Now’ means the action is in a long state, continuous and a new situation. (Zhu, 2019). By putting “le” after the verb phrase or at the end of the sentence, for instance, “他是會計師了” – (He is an accountant now), it represents a continuous situation; “我吃飯了”- (I am going to have dinner now), it is then to show that a new situation is happening. The use of “le” with negation would mean ‘not exist anymore’. For example: “沒有飲品了” – there are no drinks anymore.
Liu, M. (2015). Tense and aspect in Mandarin Chinese. The Oxford handbook of Chinese
Overseas Chinese Language and Cultural Education Online. (2008). 淡淺 “了” 字教學. Retrieved from: http://www.hwjyw.com/jxyd/xskj/200803/t20080306_13666_1.shtml
Zhu, C (2019). Chinese Aspectual Particle le: A Comprehensive Guide (1st ed,) Hong Kong