选择上颌无牙颌印模托盘的标准包括()
A.中部盖过腭小凹后2mm
B.低于唇颊粘膜皱襞2mm
C.高于唇颊粘膜皱襞2mm
D.A+B
E.A+C
参考答案:D
If we have a strong will, we can overcome any difficulty ______ it is.
A.what
B.how
C.whatever
D.however
辛弃疾的词“举头西北浮云”取自于一首诗的诗句:“西北有浮云”,请问这句诗是谁的作品?