【正文】 air B． to find out how important iron is C． to find out how to do the experiment of iron39。s reaction with water and air D． to find out how to keep iron rustless Step 3 Summary Fill in the blanks according to the text. Different metals have different . When we use metals, it is to know how they with different substances. The reaction of metals with these substances can be put in . From the ， we can find that potassium reacts with oxygen and water while copper doesn39。t react with water. When we calcium in oxygen, it burns to an oxide. In the second part of the experiment, you must boil the water to make sure there is no air in it. You add some oil to the water because this air out of it. It also shows that iron does not rust in water without air in it. ， the nails rust in the tube with ordinary water in the third part of the experiment. That is how iron reacts with air and with water. 答案： Step 1 Step 2 Ⅰ . Ⅱ . Step 3 課內(nèi)合作探究 v. 膨脹；擴大 ， 擴張 ① Air expands when heated. 空氣受熱膨脹 。 ② The writer expanded his short novel into a long one. 那位作者把他的短篇小說擴展為長篇 。 ③ His pany expanded into a big one. 他的公司擴大規(guī)模而成為了大公司 。 搭配 expand on /詳述某事 You mentioned the need for extra funds. Would you expand on that? 你曾提到需要額外資金 ， 詳細說明一下好嗎 ？ 單詞積累 expansion n. [U]膨脹；擴張 expansive adj. 廣闊的；遼闊的 即學即用 語法填空 —Our pany has ________(expand) its business in Stanford by opening a new branch office there. —Congratulations! 答案： expanded 題意： ——“ 我們公司在斯坦福新創(chuàng)立了一家分公司 ， 拓展了業(yè)務(wù) 。 ” ——“ 祝賀你們 。 ” 此處為現(xiàn)在完成時 。 2． substance n. [C] 物質(zhì) This is a chemical substance. 這是一種化學物質(zhì) 。 辨析： substance, matter Sometimes changes take place in matter and the substances never return to their former condition. 有時物質(zhì)發(fā)生變化 ， 再也不會恢復(fù)到原來的狀態(tài) 。 substance 是具體的 “ 物質(zhì) ” ，為可數(shù)名詞。 matter 是 “ 物質(zhì) ” 的總稱，為不可數(shù)名詞。 即學即用 單詞拼寫 Heroin is an illegal s________. 海洛因是一種違禁品 。 答案： substance 3． contract vi.amp。 ；簽署 n． [C]合同 ① The tunnel contracts to a narrow passageway as you go deeper. 再往深處走 ， 隧道縮小成了一條窄窄的通道 。 ② You shouldn39。t make a contract until you have studied provisions carefully. 你應(yīng)該先仔細研究合同的條款 ， 然后再簽訂 。 搭配 contract(wih) sb. to do sth. 就某事與某人簽訂合同 enter into/make/sign a contract簽合同 即學即用 完成句子 You should see your stomach ________ and expand when you breathe in and breathe out. 答案： contract 題意：當你吸氣和呼氣時 ， 你應(yīng)該看到你有腹部收縮和擴張 。 contract“ 收縮 ” ， 符合題意 。 4． electrical adj. 與電有關(guān)的；用電的 An electrical engineer makes machines that use electricity. 電機工程師制造用電的機器 。 辨析： electrical, electric electrical 表示與電 (學 )方面有關(guān)的，指 “ 電的，電氣的 ” 。如： electrical engineering電機工程學。 electric 表示 “ 由電產(chǎn)生的 ” 或 “ 帶電的 ” 。如：electric light 電燈； electric current電流。 ① The cooker isn39。t working because of an electrical fault. 這個炊具不能用了 ， 因為出了電氣方面的故障 。 ② The heavy freighter is driven by electric motor. 這輛重型運輸汽車是由電動機驅(qū)動的 。 即學即用 用 electrical, electric填空 ① The fire was caused by a(n) ________ fault, so the man who was in charge of electricity should be to blame. ② We cannot imagine life without ________ lights. ③ Now a lot of ________ equipment is needed for large stages. 答案： ① electrical 題意：大火是由電力故障引起的 ， 因此應(yīng)該責備負責電的那個人 。 electrical“ 電的；與電有關(guān)的 ” ， 符合題意 。 ② electric electric lights電燈 ③ electrical electrical equipment電設(shè)備 5． react vi. (化學 )反應(yīng)；反對 ， 反抗 ① When we use metals, it is important to know how they react with different substances, for example, water and oxygen. 當我們使用金屬時 ， 了解金屬和諸如水 、 氧氣之類的不同物質(zhì)如何發(fā)生反應(yīng)很