某校高中生有2700人,其中高一年级900人,高二年级1200人,高三年级600人,现采取分层抽样法抽取容量为135的样本,那么高一、高二、高三各年级应抽取的人数分别为 ______。
A、45,75,15D
由题意可知高一、高二、高三各年级人数之比为900:1200:600=3:4:2,则高一、高二、高三各年级应抽取的人数分别为:45,60,30
Thebackgardenofourhousecontainsalawn,()verypleasanttositoninsummer.
Ibelievethatremark____fromwhatyousaidyesterday.
Mymotherwasdeterminedtohelpthoseinneedandshewouldhavebeenimmenselyproudofwhathasbeenachievedtheselast20years.Theitalicizedpartinthesentenceexpresses_______.
—Haveyoufinishedthework?
—Notyet,butnomatterhowharditis,we'llkeep___untilwemakeit.
Thethreementriedmanytimestosneakacrosstheborderintotheneighboringcountry_____bythepoliceeachtime.