2018年共发生（）起一般差错，（）起严重差错

Water and air are _______ to human beings. We can not live without them.

When the airplane takes off, the passengers are told to _______ their seat belts.

This is not what we asked you to do. You can not get more pay for the _______ work.

The time is not far away _______ modern communications will become widespread in China＇s vast countryside.

Five-year-old children are too young to go to school, ________?

After Yang Liwei succeeded in circling the earth, ______ our astronauts desire to do is walk in space.

What surprised me was not what he said but _______ he said it.

How wonderful! The _____is made of _________.

______ is often the case, we have worked out the production plan.

The news that we are going outing _______ a rush of excitement.