So far no life has been found outside the earth, but while some scientists are actively searching for living things in outer space, others firmly believe there ______.
A.mustn’t be
B.may not be
C.can’t be
D.won’t be
网友回答
C解析这题考查情态动词的用法:can’t be“不可能”句意是:到目前为止没有发现生命在地球上,但有些科学家正在积极寻找生物在外层空间,别人相信不可能有。选C