— Lovely weather, isn’t it?— Yes, a bit hot, ______ ．

The ________ fact is that some European countries are heavily in debt, ________China’s economy is generally in good shape.

--___do you clean the reading room? ---Every two or three days.

 He reminded me of what I should ______ have forgotten.

As is known to all language learners, the newly learnt words will soon be forgotten unless______ used in everyday communication.