我這里有幾道英語難題，請各位前輩幫忙詳解，謝謝！1.How does it happen that the two-party system is so strongly( )(root)in American politics? veral courses of which i have taken thus far,( )(prove)to be difficult but useful for almost all students.3.After( )(interview)for the job,you sill be required to take a language test.4.The petrol tank is empty.i( )(fill)it up before we left home.5.Lack of concentration is a sign of your( )(able)to overcome the distracters.這幾個題目是要求在空白處填上括號里所給詞語的正確形式，看到這種題目，我有點暈，不知道應(yīng)當(dāng)怎樣分析和下筆，請老師幫詳細(xì)解答并翻譯成中文，好嗎？謝謝！

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1。How does it happen that the two-party system is so strongly( )(root)in American politics? 為什么兩黨政策在美國那么根深蒂固？ veral courses of which i have taken thus far,( )(prove)to be difficult but useful for almost all students。在我目前所選的幾門課程當(dāng)中，經(jīng)濟(jì)學(xué)被認(rèn)為是對幾乎所有學(xué)生都很困難而又實用的一門課。3。After( )(interview)for the job,you sill be required to take a language test。職務(wù)面試過后你將被要求參加一個語言測試。4。The petrol tank is empty。i( )(fill)it up before we left home。油箱空了，我本該在出門之前加滿油的！5。Lack of concentration is a sign of your( )(able)to overcome the distracters。注意力不夠集中是你在克服困境時的一處硬傷。1。rooted2。 has been proved erviewing ouldhavefilled5。 disability第三題，我又仔細(xì)想了一下，確實有些棘手！如果用名詞形式，那么至少前面應(yīng)該加上一個冠詞才好啊。各位看看能不能填having interviewed?。