要得到$y=3\sin \left(2x+\frac{\pi }{4}\right)$的图象，只需将$y=3\sin 2x$的图象（   ）.

    After you go to college, you'll find you have to buy a lot of textbooks.____If you want to make ends meet and successfully make it through college, you have to find ways to save on college textbooks. Here are some of the tips that would help you cut back and manage your book expense.

    ____The first thing you want to do when you need a specific book is to go to the bookstore. But the most effective way to save money on college books is to stay away from the bookstore. While it is more convenient to purchase textbooks in the bookstore, it could cost you a lot of money.

    Buy your books online. You can save a lot of money when you purchase your books online. You can buy college textbooks from Amazon, Half, CENGAGE Learning, Barnes&Noble and other websites. If you want to save money on college books，it is best to check BigWords.____

    Rent your college textbooks. If you feel you are not going to use the book after the end of the semester, it is best to rent it instead.____You can check campus book rentals, bookbyete, bookrenter, chegg and ecampus. This can save you a lot of money on textbooks.

    Check your university library. ff you do not need the book all the time, it is best to do your research in the university library instead.____In this way, you can ensure the book is available when you need it. You can also use the interlibrary loan system.

A. Do not go to the bookstore.

B. You can rent books from other students.

C. College textbooks can be very expensive.

D. Buy books from second-hand bookstores.

E. Many websites and booksellers rent books.

F. You'd better order the book you need ahead of time.

G. This website will help you find promotions, discounts and other deals.

阅读下列材料:

材料一　

材料二　他说,当时欧洲经济濒于崩溃,粮食和燃料等物资极度匮乏,如果没有大量的额外援助,就会面临性质非常严重的经济、社会和政治的危机。

材料三　赫鲁晓夫和美国总统肯尼迪的较量：

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