mr. smith often (teach)___ class9A, but this morning he (teach)_class9b

`-` teaches-is teaching

`->` Hiện tại đơn : S + V-es,s

`->` Chỉ thói quen.

`->` DHNB : often

`->` is teaching

`->` HTTD : S + am/is/are + V-ing

`->` Dùng HTTD mang nghĩa tương lai.

`->` DHNB : this morning

`answer:` teaches `-` is teaching

`-` often `-` HTĐ
`-` HTĐ: `(+)` S + V(s/es) + O
`-` Mr.Smith `-` danh từ số ít + Vs/es

`-` this morning `-` HTTD

`-` HTTD: `(+)` S + am/is/are + V_ing + O
`-` he + is.