Developing new technologies are time-consuming and expensive.

Câu 5: The earth is the only planet with a large number of oxygen in its atmosphere.

A novel is a story long enough to fill a complete book, in that the characters and events are usually imaginary.

The leader demanded from his members a

serious attitude towards work, good team spirit, and that they work hard.

Not until he got home he realized he had forgotten to give her the present.

The assumption that smoking has bad effects on our health have been proved.

Regarding as one of the leading figures in the development of the short story, O Henry is the author of many well- known American novels.