Having ________ about your suggestion for a few days, i've decided to support the project.
Answers
Having thought about your suggestion for a few days, I've decided to support the project.
Answer:
Thought
Explanation:
It is very common to start a sentence with "ing" form of a verb, and if the verb is “Have”, then also it doesn't affect the grammar of the sentence. The verb have means possess, hold, experience, etc. Therefore, as the question suggest that the user was having thought meaning experiencing thought about the other person's project but by thought and not any other tense, now as the sentence tells us that the user was thinking about the suggestions for past few days, meaning the thinking was ongoing from past to present proving the thinking to be continuous and as the thinking of the suggestions are not happening in the present not future proves that the sentence is in progressive past continuous hence, "ing" + past participle is the correct form of grammar in the sentence.