Final answer:
The correct irregular past tense form to complete the sentence is 'a) swam.' Irregular verbs in English do not follow a simple -ed pattern and must be memorized.
Step-by-step explanation:
The correct irregular past form of the verb to complete the sentence is a) swam. So the sentence correctly reads: 'We swam very late at night.' Verbs in English can have irregular forms in the past tense, which means they do not simply end with -ed. Instead, these verbs change form in a way that must be memorized.
For verbs with old past tense forms that end with -t, it's important to remember the correct past tense form. For example, the verb 'teach' in the past tense is 'taught', and 'build' in the past tense is 'built'. These are just a few examples of verbs with irregular past tense forms.
When reviewing past tense verbs and their pronunciation, it's important to note that the -ed ending can be pronounced differently in different words. It can sound like [d], like in the word 'learned' or some other variations depending on the ending of the base verb.
It's always a good exercise to practice verb forms in sentences to get used to the way tenses change based on the context of the text, whether it is written in the present or past tense.
In the exercise of labeling vowels as long or short, words like 'slept' have a short <e>, while 'green' has a long <e>. Recognizing vowel sounds helps in proper pronunciation and understanding the nuances of English spelling.