根据下列句子的句意、汉语提示或英语解释，写出空白处所缺单词的正确形式；每空一词．
After so long without any word from David， Mary was starting to （give up） hope．
The （seven） Big Data Expo was held successfully in Guiyang in May，2021.
Mary doesn't （real） care if her friends are the same or different.
If I'm available tomorrow afternoon，I （visit）the city museum with my brother.
We couldn't do all the work by （ us）.
Look!The students （answer）the questions carefully.