Breakdown of Ей надо проверить сигнализацию, как бы мошенник не вошёл в здание.
не
not
она
she / it (for a feminine noun)
здание
building
в
in / to (direction)
Questions & Answers about Ей надо проверить сигнализацию, как бы мошенник не вошёл в здание.
Why is the past tense verb вошёл used here when we are talking about a future risk of the scammer entering?
This is the standard structure for clauses of apprehension (fearing a negative outcome). After the phrase как бы не, which means lest or in case, Russian requires the past tense, even though it refers to a potential future event. The particle бы almost always triggers the past tense in conditional and subjunctive structures like this one.
Could I use чтобы мошенник не вошёл instead of как бы мошенник не вошёл?
You could, but it changes the nuance. The phrase чтобы не expresses a direct purpose, meaning in order that the scammer does not enter. The phrase как бы не expresses apprehension or precaution against an unwanted possibility, meaning in case the scammer enters or lest he enter. It implies a sense of worry about what might happen.
Why does the sentence use в здание in the Accusative case rather than в здании in the Prepositional case?
The verb вошёл indicates motion into a place. In Russian, when you are talking about the direction of a movement, you use в plus the Accusative case. If you were describing where someone already is located, you would use в plus the Prepositional case.
Why does the sentence start with the Dative pronoun Ей instead of the Nominative Она?