如图所示,用开瓶器在A处用力开启瓶盖时,开瓶器是 ____杠杆.
_____ the students came from different countries, they got along quite well in the summer camp.
利用作角平分线的方法,可以把一个已知角( )
已知向量 =(2,﹣1)与向量 共线,且满足 =﹣10,则向量 =____.