英语的词形变化
1.Hefelldownandbrokehisarm.Hemustbe___(careless)nexttime.
2.ShemustreadanduseEnglish___(often)thanbefore.
3.Shewillgetbetterresultsifshe___(do)herbest.
4.Theyaregoingtolearnthe___(twelve)lessontomorrow.