5. (5 points) From the numbers $1, 2, 3, 4, \cdots, 30$, if you arbitrarily select 10 consecutive numbers, the number of situations where there are exactly 2 prime numbers is:
cases
4
【Analysis】A natural number, if it has only 1 and itself as factors, such a number is called a prime number; a natural number, if it has other factors besides 1 and itself, such a number is called a composite number; hence the answer. Among 10 prime numbers, if 10 consecutive numbers are chosen from the 30 numbers $1, 2, 3, 4, \cdots, 30$, the situations where there are exactly 2 prime numbers are: $18 \sim 27, 19 \sim 28, 20 \sim 29$, or $21 \sim 30$, which gives 4 cases; therefore, the answer is: 4.