问题 选择题

下列有关命题的说法错误的是(  )

A.命题“同位角相等,两直线平行”的逆否命题为:“两直线不平行,同位角不相等”

B.“x=1”是“x2-4x+3=0”的充分不必要条件

C.若p∧q为假命题,则p,q均为假命题

D.对于命题p:∃x0∈R,使得x02+2x0+2≤0,则¬p:∀x∈R,均有x2+2x+2>0

答案

对于A,命题“若p,则q”的逆否命题应该是“若非q,则非p”

所以命题“同位角相等,两直线平行”的逆否命题为

“两直线不平行,同位角不相等”,A是不错的;

对于B,“x=1”成立时,“x2-4x+3=0”必定成立

反之,若“x2-4x+3=0”成立则“x=1或x=3”,不一定有“x=1”

故“x=1”是“x2-4x+3=0”的充分不必要条件,B是不错的;

对于C,若“p∧q”为假命题,说明p,q当中有假命题,可能有一个,也可能有两个

不一定p、q均为假命题,故C是错误的;

对于D,命题p:∃x0∈R,使得x02+2x0+2≤0,是一个存在性命题

它的否定应该是改量词为任意,再否定结论

∴¬p:∀x∈R,均有x2+2x+2>0,D是不错的.

故选C

完形填空

The U.S. Master Golf Tournament(美国高尔夫大师赛) is one of the big four games in professional golf. This year, Guan Tianlang, a fourteen-year-old Chinese, has become a well-known as the youngest player in the 77-year history of the game. And he won the best-performing amateur(业余选手). He had a hard time in the game, but he said it was a wonderful experience for him.

At the age of 4, he started learning golf from his father. Many people think he is a smart golfer. Even Ben Crenshaw, a two-time Masters winner, praised(称赞) Guan’s performance after playing with the boy. “He’s very confident(自信) and patient. He never played in a hurry, ” he said to the USA Today.

Guan makes the world know him not only with his game, but with his English as well. He answered the reporters’ questions with his perfect English. In fact, English is just one of favorite subjects. He also likes maths and history very much. At school, Guan is just like any other boy of his age. He goes to regular classes. He enjoys basketball and Kobe Bryrant is his favorite basketball player. He is always trying to get food grades and find time to practice golfing. He wants to win a major one day, but he said, “There’re still a lot of things to learn to improve. So nothing to rush.”

小题1:Who is Guan Tianlang?

小题2:What does Crenshaw think of Guan?

小题3:How long is the history of the U.S. Master Golf Tournament?

小题4:How did Guan feel about the time he had in the game this year?

小题5:What can we learn about Guan from the last paragraph?

单项选择题