On hearing the news of her father's death, she fainted. When she __________________________________.
Giải thích
Đáp án đúng: When she heard the news of her father’s death, she fainted.
"When + mệnh đề" = "On + V-ing."
Dịch nghĩa: Khi nghe tin cha mất, cô đã ngất xỉu.