Conditional Sentences (Kalimat Berkondisi)

Kalimat berkondisi atau kalimat yang mengandung “if” mempunyai dua bagian: Anak kalimat yang mengandung “if” dan induk kalimat.
Contoh:
If it rains I shall stay at home.
If it rains dalam kalimat di atas adalah anak kalimat, sedangkan I shall stay at home adalah induk kalimat.

Ada tiga tipe kalimat berkondisi. Masing-masing mempunyai pasangan tenses yang berbeda. Masing-masing tipe mempunyai bentuk variasinya masing-masing. Bagi siswa yang baru belajar kalimat ini hendaknya jangan memperhatikan bentuk-bentuk variasi itu dahulu, tetapi berkonsentrasi pada bentuk dasarnya saja.

1. Kalimat Berkondisi tipe 1; kemungkinan (probable)
Pola:
If + Subjek + kt. kerja 1, Subjek + will/shall + kt. kerja 1 (future)

Contoh: If he runs, he will get there in time.
The cat will scratch if you pull her tail
Kalimat berkondisi tipe 1 ini menunjukkan bahwa perbuatan dalam anak kalimat “if” mungkin terjadi. Perhatikan bahwa induk kalimat ini bermakna sekarang (present) atau akan datang (future), jadi ada kemungkinan akan terjadi.

Bentuk variasi:
Will, shall dalam induk kalimat bisa digantikan oleh may, might, can, must, should, atau bentuk command and request, atau kata kerja 1 lainnya.
Contoh:
If the fogs get thicker, the plane may be diverted.
If you want to lose weight, you should eat less bread.
If you heat the ice, it turns to water.

Kata kerja 1 dalam anak kalimat “if” bisa digantikan oleh kata kerja –ing (present continous).
Contoh:
If you are waiting for the bus, you’d better join the queue.
If you are looking for Peter, you’ll find him uopstairs.
If you are staying for another night, I’ll ask the manager to give you a better room.

2. Kalimat berkondisi tipe 2
Pola; If + S + kt. kerja 2, S + would + kt. kerja 1 (conditional)


Contoh:
If I had a map, I would lend it to you.
If someone tried to blackmail me, I would tell the police.
Tidak ada perbedaan dalam waktu (time) antara Kalimat berkondisi tipe 1 dan tipe 2. Tipe 2, seperti halnya tipe 1, mengacu pada masa sekarang (present) atau masa datang (future), dan past tense dalam anak kalimat “if’ bukanlah past tense yang sebenarnya.

Kegunaan tipe 2:
1) Jika pengandaian bertentangan dengan kenyataan;
If I lived near my office, I would be in time for work.
If I were you, I would plant some trees round the house.

2) Ketika kita tidak mengharap perbuatan dalam anak kalimat “if” akan terjadi.
If a burglar came into my room at night, I would scream.
If I dyed my hair blue, everyone would laugh at me.

3) Kadang-kadang, agak membingungkan, tipe 2 bisa digunakan sebagai alternatif tipe 1 untuk menyatakan rencana atau saran yang sangat mungkin terjadi.
Will Mary be in time if she gets the ten o’clock bus?;
No, but she’d be in time if she got the nine-thirty bus, atau
No, but she’ll be in time if she gets the nine-thirty bus.
We’ll never save 100 dollars—If we each save 10 dollars a week, we would do it in ten weeks.

Bentuk variasi:
Bentuk variasi induk kalimat
(a). “would” dalam induk kalimat bisa digantikan oleh “might” atau “could”:
If you tried again, you might succeed.
If I knew her number, I could ring her up.
If I had a permit, I could get a job.
(b). “would, might” bisa ditambah be dan kata kerja –ing:
If I were on holiday, I would be touring Italy.
©. “would” bisa diganti dengan kata kerja ke 2:
If anyone interrupted him, he got angry.
If there was a scarcity of anything, prices of that thing went up.

Bentuk variasi anak kalimat “if”:
(a). “if” + past continous
If I were going by air, I would feel much happier
If my car was working, I would drive you to the station
(b) “if” + past perfect
If he had taken my advice, he would be a rich man now.


3. Kalimat berkondisi tipe 3
Pola: If + S + had + k. kerja 3 (past perfect), S + would have + kt. kerja 3 (perfect conditional)


Tipe 3 ini menunjukkan bahwa sesuatu tidak bisa dilaksanakan di waktu yang lalu karena syarat dalam dalam anak kalimat “if” tidak terpenuhi.
Contoh
If I had known that you were coming, I would have met you at the airport. (But I didn’t know, so I didn’t come.)
If he had tried, to leave the country, he would have been stopped at the frontier. (But he didn’t try.)

Bentuk variasi:
(a.) “would” bisa diganti dengan “could atau “might”
If we had found him earlier, we could have saved his life.
If we had found him earlier, we might have saved his life.
(b.) “would have+ kt.kerja 3” bisa diganti dengan “would have been + kt. kerja –ing.”
If Tom’s boy had not been there, I would have been sitting in front.
(c.) Past perfect continous bisa digunakan dalam anak kalimat “if”
If I hadn’t been wearing a seat belt, I would have been seriously injured.
(d.) Kombinasi tipe 2 dan 3 memungkinkan:
If I had caught that plane, I would be dead now. (atau I would have been killed.)
If I had worked harder at school, I would be sitting in a comfortable office now.
(e.) “Had” bisa ditempatkan di depan dan “if” dihilangkan:
Had you obeyed orders this disaster would not have happened.

***
sumber: A.J. Thomson, A.V. Martinet Practical English Grammar