I have bought _____ useful reference books _____ I don’t know which one to start with.

It’s high time we _____ strict measures to stop pollution.

_____ with the developed countries, some African countries are left far behind in terms of people’s living standards.

No one except two servants （ ） late for the dinner.

Yon don’t have the right to blame me _____ being late， for I was busy typing your business invitations.

Without his wartime experience, Hemingway _____ his famous novel A Farewell to Arms.

Do what you think is right, （ ）they say.

You might not like the way Sam behaves, but please be kind to him.______ , he is your grandfather.

Whenever we planned our vacations， mother could always offer some _____ suggestions.

I don’t know whether he is still （ ） in collecting coins. He used to be, but that was several years ago.

The department head insisted that he _____ absolute authority to regulate office work.

The volcanoes that raised the islands are still （ ） places.