Explanation

The correct sentence is: "This is the house she was referring to."

"The" is used here to refer to a specific house that is being discussed or identified.

Explanation

The correct sentence is: He was generous to the helpless orphans.

"The" is used to specify a particular group (helpless orphans in this case).

Explanation

The correct sentence is "Sara is an honest girl".

The article "an" is used because the letter "h" in "honest" is silent and the letter "o" is a vowel. 

Explanation

"An" is used before "orange" because it starts with a vowel sound.

"A" is used before "mango" because it starts with a consonant sound.

Explanation

"An" is used before words starting with a vowel sound.

"Important" begins with a vowel sound (/ɪ/), so "an" is appropriate.

"A" is used before consonant sounds.