I’m afraid you missed a fantastic lecture yesterday. How come you were absent from it?—If you _______ know, I asked for a day off and visited a relative of mine in hospital.

Theresearchersfoundclearandconvincingevidence_________happinessisthekeywhenitcomestobetterhealthandlongerlives.[ ]

13．A new simplified desktop computer has been developed for people aged over 60 to make them _________with PC and the Internet.

I saw a woman running toward me in the dark.Before I could recognize who she was, she had run back in the direction _______ she had come.

There is so much noise around his flat that he feels mad.