6. 

1. I went to Mar del Plata. I have a lovely day. ⇒ had 

2. Last night I forgot my history book in your house. ⇒ Không có lỗi 

3. I went shopping yesterday. I brought a very nice skirt and a sweater. ⇒ bought 

4. I enjoyed my holiday. The weather was hot. I liked hot weather and I like it when the sun is shining.

⇒ Liked → like

    Like → liked 

    is → was

Exercise 6:

1. have → had (thì Quá khứ đơn, have → had)

2. No mistake

3. brought → bought (brought viết sai chính tả → bought: mua)

4. liked → like (thì Hiện tại đơn)

    Like → liked (thì quá khứ đơn)

    is → was (thì quá khứ đơn)

Xin hay nhất!