阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空。

    I had a school trip last May Day. We spent ____ first four days in Paris. We had a sightseeing of the city, and we ____ (visitor) some of the famous places ____ the Eiffel Tower and the Louvre. From Paris we traveled down to the south of ____ (French) near Marseilles by boat. We spent ____ (fifth) days there. There we had a lot of ____ (funny). We swam in the sea，and we took a lot of ____ (picture). We also did lots of sports ____ the beach. We went back a week ____ (late) by train. I think the trip was interesting. I like the food best. It was ____ (deliciously).

已知互异的复数a，b满足ab≠0，集合{a，b}={a²，b²}，则a+b=（　　）

一个圆柱的侧面展开后是一个正方形，这个圆柱的底面半径和高的比是(    )。