-- Did you read a book about customs last week?-- Yes, I found ______ very useful to know the customs of foreign countries.

New technologies have made ____ possible to turn out new products faster and at a lower cost.

I forgot to bring my pen, would you please lend ________ to me?

People who eat a balanced diet should be healthier than _____ only eat biscuits. 

— How pleasant 　　　 is to go fishing with my father! — Yes. Parents and children should spend more time together.