Once can function as both a time and conditional conjunction in English. When used as a time conjunction, “once” denotes a specific point in time, signaling that something happened at least once or happened at a particular time in the past. For example, “I met her once at the party.”

On the other hand, “once” can also serve as a conditional conjunction, indicating that something will happen only if a particular condition is met. For instance, “Once you finish your homework, you can go out to play.” Here, “once” establishes the condition (finishing homework) that must be met for the subsequent action (going out to play) to occur.

In marking the completion of an event, “once” is often used to indicate that a particular action or situation occurred at a specific time in the past or happened just one time. When establishing a condition, “once” sets the requirement that needs to be fulfilled for another action to take place.

The meaning of “once” can shift depending on its context within a sentence. Understanding whether “once” is functioning as a time marker or a conditional conjunction can help discern its precise meaning in each instance. It is essential to pay attention to the verb tense and surrounding words to determine the intended usage of “once” in a sentence.