Past tense in English
In English, past tense is used when the event time is preceded by the speech time. For example, the speaker utters his experience in the past in example (1a). “Came” would be used instead of the present tense “come” as the event time has already passed when the speaker talks about his experience. However, the event time might not always be included in the statement or utterance. The event time and tense can be identified by considering the boundedness and perfectivity of the event, whether it is an ongoing or terminated event.
Past tense in Chinese
In Chinese, a Chinese verb's form does not change regardless of speech time, but a time adverb or an aspect particle is to signify past, present, or future. The markers “過” and “了” are added to report an event that happened before and represent the realization or actualization of an event, but they are semantically different. When “了” is placed after a verb, it emphasizes the action but not the completion of an event. When “過” is added after a verb, the experience is highlighted. In example (1b) “家裡來了客人”, it means there were some guests in the house. They came and may not leave at that moment. However, “家裡來過客人” as shown in example (1c), means that the guests came but have left already. The indication is therefore that the status of “verb+了” remains unchanged; however, the status may be different when using “verb+過”.
Past tense and Conditional clauses
Past tense can also be applied in other situations in English, such as the second and third conditional sentences, which are also used in Chinese in different ways.
Second conditional clause
This second conditional clause indicates the presupposition described is less likely to have happened or counterfactual. Simple past tense is used to describe the least possible in the presupposition. However, unlike the ways explained above, the second conditional clause does not use past tense to explain things that happened but something unreal and might not happen. For instance, past tense is applied in “If I were a baker, I would bake a cake.”, as shown in (2a) to present the idea that the speaker was not a baker and he/she cannot be a baker at the speech time. However, it is not restricted to the speaker's preference to become a baker in the future.
Conditional sentences are also widely applied in Chinese, but the ways to express them are different from English. Associated words and adverbs are used to form specific sentence patterns, like “如果... 就...”, “如果... 一定/應該...”, to emphasize consequence. Referring to example (2b), the sentence structure “如果... 就...” is used to indicate the impossibility of the assumption. The sentence in (2a) can be translated into “如果我是一個烘培師，我就會烤一個蛋糕。”
Third conditional clause
A similar application of past tense “past perfect” and “past particle” can also be found in the third conditional clause to illustrate the assumption that something has already passed. Yet, the situation described in the premise has not occurred in reality, and the result under this assumption cannot be found either. In example (3a), “If you had come, you would have known what happened.” However, the semantic meaning indicates that “you” did not come, so “you” did not know what happened.” It is discovered that English speakers prefer to use past tense as a component to delineate the presupposition if the hypothesis is about something that could have happened but did not occur. In Chinese, the third conditional clause is slightly changed to “如果... 一定/應該...” to show the certainty that the present situation would have been different if you had/had not done something at a particular moment in the past. For instance, example (3a) can be translated to (3b) “如果你有來，你一定會知道發生了什麼”.
