今天我们这儿来了一位新朋友( )
A:We have a new friend today.
B:We have an old friend today.
Paula is pleased that she _________ her lost watch.
Amy:Who's that ____ (bay boy)?
Chen Jie: He's ____ (me my) brother.
Amy: Is she ____ (you your) mother?
Chen Jie: Yes , ____ (She she ) is.
Amy: Is he ____ (you your) father?
Chen Jie: No, he isn't. ____ (he's He's ) my teacher!
如图所示,固定斜面倾角为θ,一个物体在与斜面平行的拉力F作用下,沿斜面向上运动一段距离L.在此过程中,拉力F对物块做的功为( )
金属铈(稀土元素)性质活泼.铈常见的化合价为+3和+4,氧化性:Ce4+>Fe3+>I2.下列说法正确的是( )