x100x1001. It is probable that, some time in the tenth century, black powder was first
compounded from its basic ingredients of saltpetre,
charcoal and sulphur.
主语从句it 作形式主语真正的主语是that 从句
2. One advantage of being an only child is that there is less arguing within the
family.
表语从句•
3. Asimple analogy can help us to understand how a rocket operates 宾语从句
4. There is no doubt that “crimes against the person” rise in the summer, when theweather is hotter and fall in the winter, when the weather is colder.同位语从句