The companies are working together to create _________ they hope will be the best means of transport in the 21st century. 

The reason______ he gave for being absent from school was ______ he had to attend his sick mother at home.

-- How long do you think it will be ____ the USA recovers from the losses of the financial crisis? -- Perhaps four or five years.

It’s more than half a century _________ my grandfather joined the Party and became a servant to the people.

（湖南省怀化市2014年高三第二次模拟考试）25. ______ all of you are top students, only one will be chosen for the coming competition.