埋弧焊机按焊丝的数目分类，可分为单丝和多丝埋弧焊机。( )
参考答案：对
—Who's singing in the next room?
—It _____ be her. She has gone to New York. [ ]
A. can't
B. must
C. shouldn't
D. can
前瞻记忆指的是什么通常有哪些研究方法
