hi i hope i can help
answer :
because we add 'that' or Adding “ing” to the ending of a verb in the English language changes both the meaning and the function of the verb. In some cases, it causes the verb to act as a noun or adjective, whereas in others, it changes the tense of the verb.
Verb FunctionAdding “ing” to verbs can change the tense of the verb to various instances of the continuous, denoting ongoing actions. In the sentence, “I’m singing opera,” the verb “singing" denotes the present continuous tense. In, “I’ve been singing opera,” the phrase “been singing" portrays the present perfect tense. The sentence, “I was singing opera,” uses “was singing" in the past continuous tense. “I’ll be singing opera tomorrow night” portrays “be singing" in the future continuous tense.
but anways here 2 web sites that can help
https://learnenglish.britishcouncil.org/grammar/beginner-to-pre-intermediate/verbs-followed-by-ing-or-by-to-infinitive-1
https://www.theclassroom.com/adding-word-change-its-meaning-5146849.html
