Excuse me! Is this your pen?
No, it's not _____. It's Tom's.( )
hers
his
mine
yours
在等比数列中,,,,则项数为 ()
已知=(cos 40°,sin 40°),=(sin 20°,cos 20°),则等于()
若集合,,那么=()
已知复数则|z|=()
若曲线与曲线存在公切线,则的