一、当问及时间、距离以及其它用数字表示的细节时，有时需要进行计算方能得出答案。此时要把计算过程简单列出，不可随意心算一下即确定答案。 例一：Directions: Read the following passage and choose the best answer to each question. The Flag of the U.S. — The Stars and Stripes
The history of the flag of the U. S. has become so cluttered by myth that hardly any facts can be established. One thing all that the Stars and Stripes originated as the result of a resolution adopted by Congress June 14, 1777. It read:Resolved: that the flag of the United States be thirteen stripes,alternate red and white; that the union be thirteen stars, white in a blue field, representing a new constellation.
The flag of 1777 was used until 1795. Then, on the admission of Vermont and Kentucky to the Union, Congress passed an act that after May 1, 1795, the flag should have 15 stripes and 15 stars.
When new states were admitted it became evident that the flag would become burdened with stripes. Congress thereupon ordered that after July 4, 1818, the flag should have 13 stripes, symbolizing the 13 original states; that the union have 20 stars, and that whenever a new state was admitted a new star should be added on the July 4 following the admission.
The 50 — star flag of the United States was raised for the first time officially on July 4, 1960, at Fort McHenry in Baltimore. The 50th star had been added for Hawaii, a year earlier the 49th, for Alaska. Before that, no star had been added since 1912, when New Mexico and Arizona were admitted to the Union.
1) Since 1777, the U.S. flag has changed its design ___________ . (A) twice (B) 3 times (C) 5 times (D) more than 5 times
2) In 1912, before July 4, the U. S. flag had ___________ . (A) 15 stars (B) 20 stars (C) 46 stars (D) 48 stars
3) The 49th and 50th states to join the U.S.A. were, in their correct order, ___________ . (A) Alaska and Hawaii (B) Hawaii and Alaska (C) New Mexico and Arizona (D) Arizona and New Mexico
4) Congress decided in 1818 that the U.S. flag should have 13 stripes because ___________ . (A) since 1777 it had always had 13 stripes (B) since 1777 it had always had more than 13 stripes. (C) In 1818 there were only 13 states in the Union of the U.S.A. (D) At the founding of the Union of the U.S.A. there had been only 13 states.
问题(1)要求回答美国国旗图案自1777年以来变化了几次。回答这样的题目须把文中所有提及1777年以来美国国旗变更次数的关键词语划出：1795；July 4, 1818; since 1912; a year earlier the 49th; July 4, 1960
问题(2)提问的是1912年7月4日以前的情况。由于新墨西哥和亚里桑那于1912年7月4日加入联邦，国旗上星的数目增至48颗。因此，1912年7月4日以前国旗上的星数应为46颗。正确答案为(C)。 问题(3)的答案为(A)。其根据为The 50th star had been added for Hawaii, a year earlier the 49th, for Alaska. 问题(4)的答案为(D)，其根据是symbolizing the 13 original states
that the Stars and Stripes originated as the result of a resolution adopted by Congress June 14, 1777. It read:Resolved: that the flag of the United States be thirteen stripes,alternate red and white; that the union be thirteen stars, white in a blue field, representing a new constellation.
