like: I was sick last week. — You were? I didn → →
1815
I was sick last week. — You were? I didn't know that. ☊ 
Tuần trước tôi ốm. - Cậu ốm á? Thế mà tôi không biết. ☊ I was sick last week. — You were? I didn't know that. ☊ Tuần trước tôi ốm. - Cậu ốm á? Thế mà tôi không biết. ☊