Now that his mother was being there, they said nothing about it. → On

Tạm dịch: Vì bây giờ mẹ anh ấy đang ở đó, nên họ không nói gì về điều đó.
Ta có cấu trúc: Now that + S + V = On account of + N/V-ing = On account of the fact that + S + V: bởi vì, được dùng trong câu để đưa ra nguyên nhân hoặc dùng để giải thích một vấn đề gì đó
→ Đáp án:
- On account of his mother’s being there, they said nothing about it.
- On account of the fact that his mother was being there, they said nothing about it.
- On account of his mother’s presence, they said nothing about it.
- On account of the fact that his mother was being there, they said nothing about it.
Notes:
- presence /ˈprezns/ (n) sự hiện diện, sự có mặt

Now that his mother was being there, they said nothing about it. → On____________________________________________________________

Now that his mother was being there, they said nothing about it.
→ On____________________________________________________________