.根据下列句子及所给汉语注释，写出空缺处单词的正确形式，每空一词。

小题1: Cindy told me it was her            (第二)time to visit Shanghai during the Expo 2010 Shanghai China.

小题2: Thanks to the policy, which the government is sending home-electric machines to farmers, they can pay much            (少的) money.

小题3: What was the most important            (发明) in the 20^th century.

小题4:People are pretty             （放松的）about time in Columbia.

小题5:We’re             (筹集)money to help the poor boy.

下列关于氧气物理性质的说法中，正确的是（     ）

A．氧气是一种淡蓝色液体

B．氧气易溶于水

C．氧气在标准状况下是一种无色气体

D．氧气的密度略小于空气