根据短文内容，选择正确答案。

      Mr. Brown lives in a nice house in a small town with his wife (妻子), Mrs. Brown. From Monday to

Friday he works in an office near his house. He is free on Saturdays and Sundays. He has a nice garden beside

his house. He likes growing flowers and he often works in the garden on Saturdays and Sundays. The flowers

are very beautiful and Mrs. Brown likes them very much. She often helps Mr. Brown.

1. Mr. Brown live in ____________ with his wife.

A. a city

B. a small town

C. a big town

2. He works _____________ days a week in his office.

A. four

B. five

C. six

3. He isn't _____________ on Saturdays and Sundays.

A. free

B. busy

C. happy

4. He likes _____________ on Saturdays and Sundays.

A. working in his garden

B. walking in his garden

C. looking at his garden

5. Mrs. Brown _____________ the flowers.

A. likes

B. doesn't like

C. often helps

与集合之外的任何解相比它们至少有一个目标函数比集合之外的解好，而其它目标函数又不比集合之外的解差的解集称为（）