邓 * * 理论的首要问题是:什么是社会主义、怎样建设社会主义。( )
参考答案:对
She_____ have gone to Shanghai for a visit. She has been discussing the papers with me for a whole day.
A.mustn’t
B.needn’t
C.shouldn’t
D.can’t
流体的抗剪和抗张能力大。