如果⋯⋯就⋯⋯
rú guǒ …… jiù ……
Expressing "if… then…" with "ruguo… jiu…"
如果…就… is the basic conditional, and the 就 is what makes it feel complete.
如果 + Condition，(Subj.) + 就 + Result
How it works
如果有困难，就给我打电话 — if you have trouble, ring me.
如果 can be dropped in speech, leaving the 就 to carry the conditional: 有困难就打电话.
就 always comes after the subject of the second clause, never at its start.
Examples
rú guǒ yǒu kùn nán, jiù gěi wǒ dǎ diàn huà
如果有困难，就给我打电话。
If you run into trouble, give me a call.
rú guǒ nǐ qù, wǒ jiù qù
如果你去，我就去。
If you go, I'll go.
rú guǒ míng tiān xià yǔ, wǒ men jiù bú qù le
如果明天下雨，我们就不去了。
If it rains tomorrow, we won't go.