Explanations:The present perfect tense is a grammatical construction used to describe actions that have occurred at an unspecified time before the present or that began in the past and continue up to the present. It is formed using the auxiliary verb "have" or "has" followed by the past participle of the main verb. The choice of auxiliary verb depends on the subject of the sentence.
For third-person singular subjects (he, she, it), the auxiliary verb "has" is used. The past participle of the verb "to write" is "written." Therefore, the correct form of the present perfect tense for third-person singular subjects is "has written."
Let's break down the formation of the present perfect tense:
1. **Auxiliary Verb**: The auxiliary verb used in the present perfect tense is "have" for first-person singular (I) and plural subjects (we, you, they), and "has" for third-person singular subjects (he, she, it).
2. **Past Participle**: The past participle of the main verb is used after the auxiliary verb. For regular verbs, the past participle is formed by adding "-ed" to the base form of the verb (e.g., "walked," "talked"). For irregular verbs, the past participle is a different form (e.g., "written," "eaten," "seen").
3. **Subject-Verb Agreement**: The auxiliary verb must agree with the subject of the sentence. For third-person singular subjects, "has" is used, while for all other subjects, "have" is used.
Here are some examples to illustrate the use of the present perfect tense with third-person singular subjects:
- He has written a novel. (The action of writing the novel occurred at an unspecified time before now.)
- She has seen the movie. (The action of seeing the movie occurred at an unspecified time before now.)
- It has rained all day. (The action of raining began in the past and continues up to the present.)
It is important to note that the present perfect tense is not used to describe actions that occurred at a specific time in the past. For that, the simple past tense is used. For example:
- He wrote a novel last year. (The action of writing the novel occurred at a specific time in the past.)
Understanding the correct formation and usage of the present perfect tense is crucial for effective communication in English, especially in formal writing and speaking contexts.