Time Clauses with "Antes que"
When organizing a surprise, you often need to get things done before someone arrives. In Portuguese, the conjunction antes que (before) is used to show that one action happens before another.
Because the event following antes que is anticipated and hasn't actually happened yet, it always triggers the subjunctive mood. Notice how the regular verbs chegar (to arrive) and revelar (to reveal) become chegue and reveles in the present subjunctive:
| We organize the party before he arrives. | Organizamos a festa antes que ele chegue. |
| They start to decorate the living room before the guests arrive. | Eles começam a decorar a sala antes que os convidados cheguem. |
| We hide the present before you reveal the secret. | Escondemos o presente antes que tu reveles o segredo. |
Exclusion Clauses with "Sem que"
To keep a secret, you must do things without anyone noticing. The conjunction sem que (without) introduces an exclusion clause—indicating that the main action happens while the second action does not.
Since the second action is avoided or hypothetical, sem que also requires the subjunctive mood. Watch how suspeitar (to suspect) and the irregular verb saber (to know) take their subjunctive forms (suspeite and saiba):
| I buy the present without her suspecting. | Compro o presente sem que ela suspeite. |
| We prepare the candles and the banner without the father knowing. | Preparamos as velas e a faixa sem que o pai saiba. |
| The employee disguises the mistake without the boss noticing. | O funcionário disfarça o erro sem que o chefe note. |