$36 \cdot 9$ Rearrange the seven letters in "CONTEST". How many of all possible arrangements have the first two letters as vowels? (For example, OETCNST is one such arrangement, while OTETSNC is not)
(A) 60.
(B) 120.
(C) 240.
(D) 720.
(E) 2520.
(36th American High School Mathematics Examination, 1985)
［Solution］Given that there are only two vowels among the seven letters, the number of permutations where the first and second letters are both vowels is $2 \cdot 5$!. However, since there are two $T$s in the given letters, the total number of permutations should be halved, which is
$$
\frac{1}{2} \cdot 2 \cdot 5! = 120 \text{ (ways) }
$$

Therefore, the correct choice is $(B)$.