A. 乙烷 B. 乙烯 C. 丙烯 D. 乙炔
A. 对 B. 错
A. fairly B. largely C. virtually D. practically
A. took up, believed B. had, thought highly of C. had, believed D. took up, thought highly of
A. was stuck with B. had little C. was used up D. had much
A. die, such B. lose validity, so C. lose validity, such D. die, so