This is______difficult problem that few students can work it out.

In order to support the big family, he worked so hard that_______ he made himself ill

We are often told by our teachers not to do such things that don’t _________a harmonious society.

How can we __________ to a changeable environment?——– By constant study and changing our ideas.

It largely the efforts of the government and those companies whether the housing prices can be brought down to a more reasonable level.