There seems to be two causes as I try to figure out __________ that prevents so many children from being as happy as before.

May I call you Ann — ________ .

Perhaps the best sign of _____ computer andinternet use pushes up demand for paper comes from the high-tech industry itself

This visit will greatly________our understanding of your great country.[ ]

The Great Wall is ____ tourist attraction that millions of people pour in every year.