有X、Y、Z三种溶液,在Na2CO3溶液中加入X,生成白色沉淀,在沉淀中加入Y,沉淀溶解并产生气体,再加入Z,又出现白色沉淀。X、Y、Z分别是( ) X Y Z
pens are long, but are short. A.Ours; their B.Our; theirs C.Our; their
Now I knowabout public signs. A.muchB.a lot C.many
There water and flowers in the vase last week. A.weren’t any B.isn’t any C.wasn’t any
—Did you have a good time on your holiday? — A.Yes,we did.B.Yes,you did. C.Yes,we have.
He likes in Summer. A.swim water B.swiming C.swimming