From 1830 onwards in the USA and from about 1870 in Canada, settlers began to move westwards and to take possession of the plains as their own.
美国自1830年起,加拿大从1870年左右起,殖民者开始向西迁移,并把平原据为己有。
Next, if it is not a story, get an idea of the organization of the book. Read the back cover and the introduction. Look at the pictures and the short texts below them. Turn to the front of the book and look at the contents. This way you can decide whether