影响下颌骨骨折骨折段移位的最主要因素是（）
A.咀嚼肌的牵拉作用
B.外力大小与方向
C.骨折段是否有牙
D.骨折线走行方向
E.骨折部位
参考答案：A
-What have they made up their minds to do during the summer vocation?
-They ______ to cycle around the country on their own. [ ]
A. are determined
B. are decided
C. have determined
D. have been decided
下列说法正确的是
A．32中含有的氧原子数是2×6.02×1023
B．N2和CO共1mol的混合气体中含有的分子总数是2×6.02×1023
C．2.3 g Na与O2完全反应生成3.6 g产物时失电子数是0.1×6.02×1023
D．1.0 L 0.1 mol·L-1NH4NO3溶液中含有的铵根离子数是0.1×6.02×1023
中含有的氧原子数是2×6.02×1023