The president stressed that young people's values determine the values of the future society, and more efforts should be made to ensure young people's cultivation of sound value systems, ________ are still in the formation stage.
| A.which | B.what | C.when | D.where | 
—The tickets for the concert have been sold out.
  —Thanks for reminding me, but I am lucky to have got .
| A.another | B.it | C.that | D.one | 
—How is your mother?
 —She_________ quite good after the operation, but she is taking a turn for the worse today.
| A.felt | B.feels | C.had felt | D.has been feeling | 
He never complains about the difficulties he has in life._______,he always has ways to overcome them.
| A.However | B.Otherwise | C.Instead | D.Therefore | 
If it the climate, I would stay here much longer.
| A.is not for | B.had not been for | C.were not for | D.would not be for |