Although he talked half an hour, he couldn't give us a good ________ of the reason why he did it.

 —Shall we go out for a walk? —Sorry. This is not the right _________ to invite me. I am too tired to walk.

We Nanjingers should try our best to make       to the Nanjing 2014 Youth Olympic Games.

These young people are now making an active ______ to beautify our city. 

Less than twenty percent of the employees in their company are women. That is to say, men are in the        .