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英語 高校生

模範解答がなくて困ってます(^^;) 助けてください!!! UNICORN English Expression1の110〜117です

>LESSON 6 EXERCISES A Choose the correct words. 1. My grandfather usually ( eats/ is eating ) rice for breakfast, but this morning he ( eats / is eating ) bread. 2. It( snows / is snowing / will be snowing ) by the time we arrive at the village. 3. What were you ( did / doing ) when I called you? 4.1( didn't hear / wasn't hearing ) the bell because I was ( listened to / listening to ) music with my earphones. 5. Everyone ( knows / is knowing ) the news. 6. This fish ( smells / is smelling ) bad. EXERCISES n A Follow the example and rewrite the sentences. ex. She is a good tennis player. (You) You are a good tennis player. nod ed sH 1. They usually watch TV in the living room. (He) 2. Two students are absent today. (last Friday) 7. I didn't answer your phone call because I ( took / was taking ) a bath. 8. My aunt is always ( complains / complaining ) about her job. 3. Every night the girl reads a book before she goes to bed. (Last night) hcar B Put the sentences into Japanese. 1. Our school festival is taking place next week. 2.I was reading comic books all the time when I was a boy. B Complete the sentences. 1.“Your racket is too old, isn't it?" Vet O d1O “Yes. I( ) going ( ) buy a new one this weekend.” 3. We are moving to Kyushu next month. 4. A duck is dying near the river. 5. She was studying English all day yesterday. (買いに行くつもり) ) do this afternoon, Emily?” (するつもり) top co 2.“what( “I think I ( 3.“When ( ) going ( ) go to the beach by bike." ) school( ) in your country?" (始まる) C Change the verbs into the correct form. 1. Look! The sun ( rise ) above the horizon. 2. My dog ( lie ) on the floor when I came home. 3.I( have ) supper when he called on me. 4.I ( belong ) to the music club in my junior high school days. 5. My sister ( play ) the piano now, but she ( not like ) playing the piano. “It( ) in April.” C Choose the correct words. 1.(Are / Do/ will ) you know about the accident? 2. Ken was afraid that it ( is / was going to / will be ) rain in the afternoon. 3. If it ( rains / rain / will rain ) tomorrow, the game will be postponed. 6. They ( take ) the exam at this time tomorrow. 4. Here ( comes / come / coming ) the sun. D Put the words in the correct order. 1.昨晩は10時前に寝ました。 I went ( bed / before / last / night / ten / to ). 2.数分で戻ります。 I(a/back / be / few / in / minutes / will ). 3. あとで電話をするって約束するよ. I(I/phone / promise / will / you ) later. ean E Answer the questions. 1. What do you usually do in the morning? 2. what did you do yesterday evening? 3. What are you going to do this weekend? 2 LANGUAGE FOCUS 6-

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数学 高校生

青チャートの例題の(3)について教えて下さい... 解説が全然ピンときません。 上:問題、下:解説

n の式で表される順列 320 重要 例題17 文字がn個並んだものを「長さnの列」 と呼ぶとき (1) 長さ3の列,長さ4の列はそれぞれ何通りあるか。 る列は何通りあるか。 (3) 長さnの列の個数をf(n)とするとき,f(n+2)=Df(n+1)+f(n) がゆ。 つことを示せ。 a (津田塾大) 基本6 (2) 辞書式配列法 の利用も列が長くなると大変。そこで (3) との関連もあり, (1)の長さ。 の列と長さ4の列を利用することを考える。 ① (1), (2) [, (3)]の問題 解法をまねる ことも有効。(2)と同じようにして, nの場合 (一般の場合)を考える。 指針> (1) 辞書式配列法 を利用し, 条件を満たす列を書き上げる。 ba を追加 f(n) $f(n+2) aを追加 解答 (1) 長さ3の列は aaa, aab, aba, baa, bab 5通り (辞書式配列で,条件に適す るものを書き上げる。 したがって 長さ4の列は aaaa, aaab, aaba, abaa, abab, baaa, baab, baba わが連続するものを除く。 金 したがって 8通り (2) aで始まる長さ5の列は, 長さ4の列の前にaを付ければ よいから,(1)より また, bで始まる長さ5の列は, 長さ3の列の前に baを付 ければよいから,(1)より (3) 長さ(n+2)の列のうち, aで始まる列は,長さ (n+1)の列の前にaを付けたもの, bで始まる列は,長さnの列の前にba を付けたもの である。 (aで始まる列は, aの次の 文字は a, bどちらでもよ 8通り い。 くbで始まる列は, bの次の 文字は a。 (2)の一般化。 5通り したがって f(n+2)=f(n+1)+f(n) 和の法則 S@

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