已知向量a与b的夹角为120°,且|a|=|b|=4,那么a·b的值为( )。
-8
The teacher asked the students .
A.if they are interested in dinosaurs
B.when was Audery Heben born
C.What they will do with the computers
D.how many trees they had planted
下列骨折造成周围组织损伤中,哪项是错误的()
A.腓骨小头和颈部骨折,可同时伤及腓总神经
B.股骨颈骨折,可致股骨头缺血性坏死
C.股骨髁上骨折可致腘动脉损伤
D.下胸壁肋骨骨折,可同时发生肝或脾破裂
E.肱骨内髁骨折,可伤及肱动脉