在组合机床上可以同时从几个方向对多个工件进行加工。( )
参考答案:对
_________ we have been classmates for three years, she hasn’t left me much impression, so I can’t remember her after graduation.
A.Since
B.Although
C.Because
D.Unless
朊病毒的主要组成成分是
A.多糖B.RNAC.蛋白质D.DNAE.脂类