How to say - If .... then ...

要是 。。。， 就 。。。
If ... , then ....
means if something happen, then what to do?
or if someone do something, then other do [something] too.
Jika ... Kemudian ...

Formula 格式 [rumus]
要是 + subject + verb, object + 就 + verb.
要是 + subjek + predikat, objek + 就 + predikat.

You can put the adverb after the subject
Kamu bisa menaruh kata keterangan waktu setelah subjek
要是 + subject + [adverb of time] + verb, object + 就 + verb.
要是 + subjek + [keterangan waktu] + predikat, objek + 就 + predikat.

Or ib you want to put the subject in the first sentence is allowed too.
atau jika kamu ingin menaruh subjek pada bagian pertama dalam kalimat juga boleh:
subject + 要是 + [adverb of time] + verb, object + 就 + verb.
subjek + 要是 + [keterangan waktu] + predikat, objek + 就 + predikat.

for example 例子 [contohnya]:

要是你喝，我就喝。
Yào shì nǐ hē, wǒ jiù hē.
要是你喝，我就喝。
If you drink [it], then I drink [it].
Jika kau minum, saya akan minum.


要是今天下雨，我就不跟你們去玩。
Yào shì jīn tiān xià yǚ, wǒ jiù bù gēn nǐ men qǜ wán.
要是今天下雨，我就不跟你们去玩。
If today falls rain, then I cannot hang out with you all.
Jika hari ini hujan, saya tidak jadi pergi bermain dengan kalian.


要是不在左邊，就肯定在右邊。
Yào shì bú zài zuǒ biān, jiù kěn ding zài yòu biān.
要是不在左边，就肯定在右边。
If [it is] not at left side, then it must be at right side.
Jika bukan disisi kiri, jadi pasti disisi kanan.


要是你現在不回去，媽媽就會生氣
Yào shì nǐ xiàn zài bù huí jiā, mā ma jiù huì shēng qì.
要是你现在不回去，妈妈就会生气
If you now not going home, then mom will angry.
Jika kamu sekarang tidak pulang, mama pasti akan marah.


Note:
In Chinese rhetorical sentences, the “if” clause usually occurs before main clause. In English sentences “is” is essential, but Mandarin Chinese equivalent for “if” 要是 can be omitted. However, in Mandarin Chinese 就 is not left out very often. Mostly 就 indicates an emphasis on next sentence after it in the whole sentence [first and second] as an consequences or react from the first sentence like in the samples above.