Дети не должны плавать одни, а то утонут.
The children shouldn't swim alone, otherwise they'll drown.
Breakdown of Дети не должны плавать одни, а то утонут.
не
not
плавать
to swim
должен
must, have to (должен, должна, должны)
дети
children
Questions & Answers about Дети не должны плавать одни, а то утонут.
Why do we use а то here instead of или?
The conjunction а то means otherwise or or else, and it introduces a direct negative consequence (drowning). Using или (or) wouldn't work as well because it simply offers a neutral alternative, whereas а то specifically warns what will happen if the rule isn't followed.
Why is the multidirectional verb плавать used here instead of плыть?
The verb плавать refers to swimming in general, swimming around for fun, or the general action of being in the water. The unidirectional плыть means swimming in one specific direction, like towards a shore. Since the warning is about playing in the water in general, плавать is the natural choice.
I learned that один means one. How does одни mean alone here?
When used to describe people or animals, forms of один often translate to alone or by oneself. Because дети is plural, the plural form одни is used to mean the children are in the water by themselves.
Why is утонут perfective? Couldn't we use the imperfective тонуть?