13.The reason is____________ smoking tobacco causes illness.
A. why B because C. that D. because of
Who does that shop assistant think he is? He behaves _______ he owned the store.
| A．even if | B．as if | C．as long as | D．if |
Nelson Mandela _________ his life to fighting for a free society________ all people live together in harmony.
| A．devoted; which | B．spent; in which |
| C．devoted; in which | D．spent; where |
The number of various educational programs is increasing, _______ important roles have been realized by more and more people.
| A．whose | B．where | C．which | D．that |
As she is a _____ visitor to our house, we look on her as a part of our family.
| A．fluent | B．frequent | C．unexpected | D．friendly |
I can’t remember when turning point occurred exactly, but it might be summer morning when I was in New York.
| A．不填；a | B．a; a | C．the; a | D．a; the |