The password consists of only the letters k, l, m, n and o. The letters of the password are written from left to right. To form a password text, the following conditions must be met. This set of letters is:

1 The password text is at least two letters and can be repeated;

2 k can't be the first;

3. If there is an L in a cipher, this L must appear more than twice;

4 m cannot be the last letter or the penultimate letter;

5. If there is k in this cipher text, there must be n;

6. Unless there is an L in this password, O can't be the last letter.

[question]

Question 1 which of the following letters can be placed after lo to form a three-letter cipher text? k； (b)l(c)m； n； (e)o .

Question 2: If a password has only three letters of K, L and M, and each word can only consist of two letters, what is the total number of words that can form a password? 1； (b)3； 6 people; (d)9; (e) 12 .

Question 3. Which of the following groups is ciphertext? klln(b)loml(c)mllo(d)nmko(e)onkm；

● Questions 4k, L, M, N, O, etc. How many ciphertexts composed of three identical letters can be formed? 1； (b)2； (c) Article 3, paragraph 4; (e)5 .

Except for one case, the following four methods can change the password mmllokn into another password. The exceptions are: (a) replace each L with n (b) replace the first M with O; (c) replace n with o; (d) move o to the right of n; (e) move the second m to the left of k.

Question 6. One of the following five groups of letters is not ciphertext, but it can be ciphertext by changing the alphabetical order. This set of letters is: (a) LLMNO; Lllknmknon Nagorno-Karabakh Autonomous Prefecture; (e)omm ll；

Question 7: Which of the following passwords can replace the letter X in this password with one of its letters, thus forming a password text that conforms to the rules? (a)mkxno(b)mxkmn，(c)xmmko，(d):xmolk； (e)xoklln .

answer

■ Answer 1 (B). As long as we remember the known condition 3, we can choose the right answer immediately.

■ Answer 2 (A). It can be seen from the known conditions 2, 4 and 5 that two of the three letters, K and M, cannot be useful under such conditions. Therefore, only one letter l is available; According to the known condition 3, we can know that there is only one password, ll, so we choose (a).

■ Answer 3 (C). Select (a) Violation of Condition 2; Select the "Violation of Condition 4" button; Option (d) violates condition 6; Select (e) Violation of Condition 4. Therefore, choose (c).

■ Answer 4 (B). Because the condition is limited to three letters, according to the known conditions 2, 4, 5 and 6, the three letters of K, M and O can be excluded first, so only lll and mn are left.

■ Answer 5 (C). Because after replacing N with O, the original password text becomes mmlloko, which violates the known condition 5, so it is wrong.

■ Answer 6 (D). When we encounter this kind of problem, we can first find out the wrong password text, and then see if we can correct it according to the conditions defined in the problem. We can find that the ciphertext in group (d) obviously violates the known condition 4, but as long as M is interchanged with any position of the first three letters nkl, it can become a completely qualified ciphertext, so we choose (d).

■ Answer 7 (E). Let's rule out one by one: X in (a) must be replaced by L to meet the known condition 6, but there is no L in this set of letters, so it won't work. (b) The ciphertext in the group itself violates known condition 4, so it has no effect. (c) is the same as (a). X in (d) must be replaced by n to meet the known condition 5, and this cipher text does not contain the letter n, so it will not work. Only choose (e) to meet all known conditions, so choose (e).