The words "sang" and "sung" are often confused, as they are both past conjugations of the verb "sing." However, "sang" is the past tense, meaning it can be used on its own to indicate singing occurred at a previous time, while "sung" is the past participle, meaning it either must be accompanied by the verb "to have" or can act as an adjective. In most verbs, the past tense and past participle are the same, but since "sing" is an irregular verb, they are different.

Using Sang

As "sang" is the past tense of sing, it is used when referring to singing that occurred at a previous time. Since it is a verb, it must be accompanied by a noun in a sentence. For example, "Mary sang the national anthem at the football game last week." In this sentence "sang" is referring to the action of singing that Mary, the noun, did last week, which is in the past.

Using Sung

The word "sung" is the past participle of the verb "sing." Past participles are tricky, as they are used in a couple of different ways. When preceded by "has," "have" or "had," they refer to the completion of an act or state in the past. However, if placed before a noun, they can also be used as adjectives. For example, "Mia had sung her heart out, but still lost the competition." In this sentence, "sung" refers to Mia having completed singing before losing the competition. In the sentence, "The sung lullaby put the baby to sleep," the word "sung" is acting as an adjective -- describing how the lullaby was recited.