an’t concentrate on his lessons recently.—-Yes, that may ________ why he did so badly in the last test.

its role in social education, the Palace Museum is quitting its admission fee for special groups on certaindates.

My sister has a habit of keeping a diary and writes down ______ happens every day．

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

What do you think of Andrew?-There are some things ________ are not easy to ________,and his rudeness is one.ide[ ]