27.As the first black President elected in American history，it’s that kind of determination(决心)___ helped Barack Obama to win the White House．
A. that B. what C．which D．this
28. If you don’t go to the concert tomorrow, _____.
A. so do I B. so will I C. nor do I D. neither shall I
29. ----Did Jack come back early last night?
----Yes. It was about eight o’clock ___ he arrived home.
A. before B. when C. that D. until
