Answer:
Regret + -ing:
When "regret" is followed by a verb in the gerund form ("-ing" form), it indicates that the speaker feels sorry or remorseful about a past action or situation. This structure emphasizes a sense of personal remorse or a feeling of disappointment about something that has already happened.
Example: "I regret telling her the truth." (This means that the speaker feels sorry for having told the truth in the past.)
In this usage, the verb in the gerund form represents the action or situation that the speaker regrets. It focuses on the action itself and the feelings associated with it.
Regret to + V1:
-When "regret" is followed by the infinitive form of a verb (V1), such as "to go," "to inform," or "to say," it suggests that the speaker feels obligated or compelled to express regret or deliver unfortunate news. This structure emphasizes a sense of duty or responsibility to convey an apology or express remorse about a specific action or circumstance.
-Example: "I regret to inform you that your application has been denied." (This means that the speaker feels obligated to inform the person about the unfortunate news of their application being denied.)
-In this construction, the phrase "regret to" is often followed by formal or serious announcements, conveying a sense of formality or the speaker's acknowledgement of a difficult or disappointing situation. It emphasizes the duty or obligation to communicate unwelcome information.