只要 … ，就 … (as long as)

If the weather holds

• A friend is worried about tomorrow's picnic. You only need one thing to go right.
• as long as只要zhǐ yào不下雨bù xià yǔ，we / us我们wǒ menthen就jiùgo去qùpicnic野餐yě cān。 — "As long as it doesn't rain, we'll go on the picnic."

as long as只要zhǐ yào + condition，then就jiù + result

• as long as只要zhǐ yào A，then就jiù B = "as long as A, then B": A is enough for B to happen.
• as long as只要zhǐ yào opens the first clause; then就jiù comes after the subject of the second.

as long as只要zhǐ yàoyou你nǐwork hard努力nǔ lì，then就jiùcan能nénglearn well学好xué hǎo。

Encouragement and easy conditions

• as long as只要zhǐ yàoevery day每天měi tiānto practice练习liàn xí，you你nǐ(modifier / structural particle)的deChinese language中文zhōng wénthen就jiùcan / will会huìmore and more越来越yuè lái yuègood好hǎo。 — "As long as you practise every day, your Chinese will keep improving."
• as long as只要zhǐ yàohave有yǒutime时间shí jiān，I我wǒthen就jiùgo去qùsee看kànyou你nǐ。 — "Whenever I have time, I'll come and see you."

as long as只要zhǐ yàohave有yǒutime时间shí jiān，I我wǒthen就jiùgo去qùsee看kànyou你nǐ。

then就jiù after the subject

as long as只要zhǐ yào…then就jiù versus only if只有zhǐ yǒu…only then才cái

• as long as只要zhǐ yào A then就jiù B: A is sufficient, it is easy: as long as只要zhǐ yàowell-off有钱yǒu qiánthen就jiùcan能néngto buy买mǎi.
• only if只有zhǐ yǒu A only then才cái B: A is the only way: only if只有zhǐ yǒuwork hard努力nǔ lì，talent才能cái néngsucceed成功chéng gōng。 — "Only through hard work can you succeed."

only if只有zhǐ yǒuwork hard努力nǔ lì，only then才cáican能néngsucceed成功chéng gōng。

Recap

Read the full reference: HSK 3 grammar — Conditional statements.