Conditional sentence
referred to as sentence modality, because of the meaning contained in the sentence is contrary to the true meaning. In English there are three types of conditional sentences, which each have their own usefulness. In a sentence modality, there are two clause, namely:
1. supposition clause, often referred to as the “if clause”
2. expectations of the clause, which in this case as the “main clause”

type1.

Used to express the things that diaharapkan would happen, for describing the things that will happen. Thus, this sentence describes a certain thing will happen, if at certain things are met.

If + subject + V1 + object: subject + will + V1

cth:

if he gives me an/the invitation, I will come to the party.

I believe that he will be angry with me if I come late.

You will pass your test if you study hard.

If he has many problems, I will help him.

Type 2

used to express things that are actually contrary to the situation now, not to predict things that will happen.

If + subject + V2 + object: subject + would + V1 + object

cth:

1.       if I were a teacher, I would teach them. (seandainya saya seorang guru, saya akan mengajarkan mereka)

2.       what would you do if you were her brother? ( apa yang akan kamu lakukan, seandainya kamu kakaknya?)

3.       If he gave the letter, I could read it. (seandainya ia memberikan surat itu, saya dapat membacanya).

4.       If he were In the room, he could see the picture. (seandainya ia di ruangan itu, ia dapat melihat gambar itu).

Type 3

used to express the things that had already happened, the impossible will happen again.

If + subject + had + V3 + object: I + would have + V3 + object

cth:

1.       if he had invited me, I could have come to the party. (seandainya ia telah mengundang saya, maka saya datang ke pesta itu)>

2.       if she had known the news, I believe that she would have gone. ( seandainya ia telah mengetahui berita itu, saya yakin bahwa ia sudash pergi).

3.       If he had been there, I could have told him the matter. (seandainya ia telah ada di sana, sebenarnya saya sudah dapat mengatakan hal itu kepadanya).

Soal:

1.       it rained very hard this morning, but mother didn’t have an umbrella with her. > if she had an umbrella, she would not have been wet.3

2.       If my parents were alive, I would not have to work for my tuition fee. > I have to earn to pay my tuition fee because my parents have died.2

3.       If he hadn’t missed the first flight, he would have been able to attend his friend’s weddign ceremony. >he didn’t attend the wedding ceremony because he missed the first flight.3

4.       I wouldn’t have gone upstairs if the lift had been working.3

5.       If only we had asked the police for directions, we would have found the place easily.3

6.       had she been there that day she would have known about the announcement. 3

7.       were he rich, he could buy the car. He is not rich and he cannot buy the car. 2

8.       I will come to your office next saturday if you are there. 1

9.       if you had returned the book yesterday, I would have finished reading it. 3

10.     if that car were mine, I would let you have a ride to go home. 2

reference : S. Paryono,  B.Inggris Pasti Lulus 100%, penerbit: Erlangga, Jakarta, 1997