1. The transitive closure matrix of the given directed graph have k elements that are 1's. What is true about k?

(A)k≤6
(B)7≤k≤10
(C)11≤k≤14
(D)15≤k≤18
(E)k≥19

26.Humans have long aspired to converse with animals； pets—________we share our homes but not a common language—are particularly tempting targets.(A) that (B) what (C) with which (D) for which

27.Flamenco is believed ________in a southern province of Spain, but no one knows exactly when or how it came about.(A) to originate (B) to have originated (C) originating (D) that has originated

28.Because of the heavy rain, the basketball game was not held as scheduled but ________to next Saturday.(A) delayed (B) cancelled (C) extended (D) postponed

29.In the 1960s, abortion in France was ________. Those who performed or received the operation would be strictly punished by law.(A) legitimate (B) illegal (C) justifiable (D) innocent

2. Consider a pair of corresponding infix and postfix arithmetic expressions. Which of the following statements is true? (A) In a postfix expression, the order of operators is from high to low precedence.(B) The infix and postfix expressions always have the same number of parentheses. (C) The infix and postfix expressions always have the same order of operands. (D) A priority queue for the operators is required when evaluating a postfix expression. (E) All of the above.

3. Below is the C++ implementation of ADTX, an unknown abstract data type. For clarity, exception handling codes are omitted. Which of the following is the most likely abstract data type implemented here? (A) stack(B) first-in-first-out queue (C) priority queue (D) linked list (E) none of the above

4. For the ADTX implementation in the previous question, after the following C++ code is executed, what is the value in adtx. x[1]? (A)6(B)9(C)3(D)7 (E)5 

5. For the postorder traversal sequence of the binary tree below, which of these statements is true?(A) Node B appears at the second position. (B) Node M appears after node D. (C) Node H appears immediately before node J. (D) The first four nodes in the sequence are all leaf nodes in the tree. (E) Node A appears between node B and node D.

6. If we make the binary tree in the previous question a threaded binary tree, which node is pointed to by a thread of node B? (A) node A (B)nodeE (C) nodeD (D)nodeF (E) node

7. For a certain binary tree, its inorder traversal sequence is EKHDAGBJFC and its level-order traversal sequence is GKBEAFHJCD. Here each letter represents a node of the tree. Which of the following statements about this binary tree is incorrect? (A) Node D is a descendent of node K. (B) There are exactly four leaf nodes. (C) Node G is the root and has two children. (D) The parent of node H is node A. (E) None of the above.