(ab)6÷(ab)2=( )
A.a3b3
B.a4b4
C.a3b4
D.a4b3
原式=(ab)4=a4b4,
故选B.
患者女,35岁,过敏体质,缺失,余留牙正常,拟采用可摘局部义齿修复
若铸造该支架,下列哪一种材料生物相容性最好()
A.A钴铬合金
B.镍铬合金
C.纯钛
D.银钯合金
E.铜合金
---- Why don’t you look ________ today?
---- My parents seem ________ with me.
A.happily, angrily
B.happy , angrily
C.happily , angry
D.happy , angry