Which of the following weapons continue the stalemate on battlefields during world war i? a-tank b-submarine c-fighter plane d-machine gun

In addition to carbon ,carbonate minerals contain

Ineed with what i should write for my research paper. my topic is history of slavery. 1800 words. all i need is what to write in each paragraphs. like when the research paper has titles for each paragraph and it explains the tile in each paragraph. for example when did slaverh begin? why did it begin like an outline.

What is the main social system that existed in ancient china?