小彰同学对物质分类进行了下列总结，如图所示：

（1）其中X表示______，Y表示______．

（2）在化合物中包括氧化物，写出一种氧化物的化学式______．

（3）分别写出由分子、原子、离子构成X的三种物质：

分子______；原子______；离子______．

根据句意或句子的语法要求，用括号中所给词的适当形式填空。

小题1:It seemed that the victim had several          (enemy).

小题2:The story          (it) is wonderful, but the actor doesn’t act well.

小题3:So far, the police         (catch) several suspects of the crime.

小题4:Be quiet! We         (not allow) to make much noise in the reading room.

小题5:As an excellent teacher, she devoted most of her time to         (teach) her students.

小题6:There is a risk of being killed here, so we will move to another place for         (safe).

小题7:Most people hate wars, we want to live          (peace) in the world.

小题8:My little sister was very sad because of her favourite dog’s      (die).