I want to know whether this sentence is valid or not which I was studying for my third language in Duolingo and got a wrong answer. The general format of the sentence is:
"There isn't a/an
<some noun>in the
There isn't a cow in the zoo.
The suggestions are:
- There aren't any cows in the zoo.
- There are no cows in the zoo.
By the way, I'm familiar with both suggestions, though more curious about my made-up first sentence from the first example. ("There isn't a cow in the zoo.")
Thanks for the answers in advance.