The new school _________ in the past five years.
A:built
B:has been built
C:has built
D:will be built
①可能有C2H4 ②一定没有C2H6 ③一定有C3H8
④一定有CH4⑤可能有C2H6 ⑥可能有C2H2.
选择最佳应答语( )