参心坐标系的原点是()。
参考答案:参考椭球中心
It took several hundred years ______ paper-making spread to western countries.
A.when
B.before
C.after
D.since
对异性服饰有特别爱好,反复穿戴以引起性兴奋,最恰当的诊断应为()
A.异装症
B.易性症
C.同性恋
D.恋物症
E.摩擦症