国开网100万⁺专项题库

A person's profile probably __.

• tells something about the person

• shows a picture of the person

A drip is __.

• a dull, boring person

• a kind of computer dating service

If something is awful, it's __.

• unpleasant and bad

• interesting and unusual

If you and your mate split up, you __.

• get engaged

• end your relationship

设P：我将去打球，Q：我有时间．命题“我将去打球，仅当我有时间时”符号化为( )．

设A（x）：x是人，B（x）：x是教师，则命题“有人是教师”可符号化为（ ）．

命题公式的主析取范式是( )．

命题公式 (P∨Q) 的合取范式是 ( ) ．

• (P∧Q)

• (P∧Q)∨(P∨Q)

• (P∨Q)

• ┐(┐P∧┐Q)

下列公式成立的为( )．

• ┐P∧┐QP∨Q

• P→┐Q┐P→Q

• 

• ┐P∧(P∨Q)Q

命题公式 (P∨Q)→R的析取范式是 ( )．

• ┐(P∨Q)∨R

• (P∧Q)∨R

• (P∨Q)∨R

• (┐P∧┐Q)∨R