条件表現N4
もし
if / suppose (softens conditionals)
Structure
もし + 条件文（〜たら / 〜ば / 〜なら / 〜ても）
Explanation
An adverb that pairs with conditionals like たら, ば and なら to strengthen the hypothetical tone, "if...". Optional, but adds a more careful nuance (もし時間があれば、行きます).
Examples
もし時間があったら、一緒に食事しませんか。
If you have time, shall we have a meal together?
もし雨が降ったら、試合は中止です。
If it rains, the match will be cancelled.
Note
もし alone does not form a condition; it must pair with a conditional expression. In speech もしも is also used. The sentence works without it, but もし makes the hypothetical clearer.