`-` CĐK Loại `1` : Diễn tả hành động có thật ở Hiện tại

`+` If - clause : Thì HTĐ : S + Vs / es

`+` Main - clause : Thì TLĐ : S + will + V

`-` CĐK Loại `2` : Diễn tả hành động không có thật ở Hiện tại

`+` If - clause : Thì QKĐ : S + Ved / V2

`+` Main - clause : Thì TLTQK : S + would + V

`-` Unless `=` If not : Trừ khi

`1`.Unless she understands the lesson , she can ask me

`2`.Unless I weren't tall , I could play volleyball

`3`.If today were Sunday , I could go for a picnic

`4`.If he found a job , he could live in the countryside

`\text{# TF}`

`1`. Unless she understands the lesson, she can ask me.

`-` Unless `=` If+...+ not

`2`. Unless I were short, I could play volleyball.

`-` If I were tall, I could play volleyball.

`=>` If I weren't short, I could play volleyball.

`-` Mà "Unless `=` If+...+ not"

`=>` If I weren't short, I could play volleyball.

`->` Unless I were short, I could play volleyball.

`3`. If today were Sunday, I could go for a picnic.

`-` Câu điều kiện loại `2`: Hiện tại không có thật

`+` If-clause: chia QKĐ

`+` Main clause: could/ should/ might/ would+ V

`4`. If he found a job, he could live in the countryside.

`-` giải thích giống câu `3`