50.What does the underlined word "seat”in the last paragraph most probably mean?
A、Focus.
B、Position.
C、Chair.
D、Center.
20.In October 2007,the Chang'e-l satellite was successfully __at Xichang.
A、launched
B、presented
C、regulated
D、engaged
Directions:In each of the following groups of words,there are four underlined letters or letter combinations marked A,B,C and D.Compare the underlined parts and iden-tdtify the one that is different from the others in pronunciation.Mark your answer by blackening the corresponding letter on the Answer Sheet.