Chemistry is the science which (1) … all other sciences. Through chemistry, we can study how things are made and what they can do. Alchemists discovered a lot of chemical (2)… before chemistry developed properly. There are three main areas of study in modern chemistry. The first is about how (3) … change when something happens to them. The second is about how things are made, and looks at the atomic (4) … of elements. The third is to look at the (5) …of elements.
Who bought sausages for today?
Did you buy sausages or fried potato for today?
I bought sausages for today, did not I?
What did you buy for today?
14. Did you have fun time with friends in summer?
Did you have fun time with friends in summer or in winter?
When did you have fun time with friends?
Last year we had fun time with friends in summer, did not we?
Who had fun time with friends in summer last year?
1. Did she look mysterious when you've seen her?
When I've seen her she looked mysterious, didn't she?
Did she look mysterious or tired when you've seen her?