`3.` Hien doesn't have Math on Monday and Saturday.( Sửa đề: not -> and)

`-` HTĐ:

(-) S+ do/does+not+V-inf+O

`4.` When does she have English?

`-` WHen : khi nào 

`->` Hỏi về thời gian 

`5.` My mother can play the piano but she can't play the guitar.

`-` clause+but+clause: nhưng

`-` can + V-inf: có thể làm gì >< can't + V-inf: không thể làm gì 

3. Hien doesn't have Math on Monday and Saturday. 

-> S +  don't/doesn't + V + O .

4. When does she have English?

-> Wh... + do/does + S + V + O? 

5. My mother can play the piano but she can't play the guitar. 

-> can do st : có thể làm gì 

-> can't do st : không thể làm gì