【单选题】( ) _____ my sister three times today but her line was always
【单选题】My sister is Class Three.
【简答题】_______ my sister three times today but her line was always busy. A.I’d phoned B.I’ve been phoning C.I’ve phoned D.I was phoning
【单选题】____ my sister three times today but her line wasalways busy. ( 05 北京春季)
【多选题】以下关于标量场的性质,不正确的是( )
C.
它的大小等于给定标量函数每单位距离的最大变化率
D.
一个标量函数在某点任意方向上的方向导数等于此函数的梯度与该方向上相应矢量的点积。
【单选题】_____ my sister three times today but her line was always busy.