A)still的意思是还是（正句）,还不/还没有（负句）等.它存有继续的含意.
例∶1) It is 12 midnight,Daisy is still outside.现在是午夜12点,Daisy还在外面.
例∶2) When we left that place,he was still inside the house.当我们离开那个地方时,他还在屋子里.
例∶3) Don’t worry,they are still young.They will have more time to learn.别担心,他们还年轻,他们会有更多的时间学习.
例∶4) I have reminded him to do that job.He is still hasn’t started it yet.我已经提醒他做那份工作,他还是没有开始做.
B)Yet的意思是还没有,通常用在负句（Negative Statement）或是问句（Questions）.
例∶5) It is 5 o’clock and Judy hasn’t arrived yet.现在是五点,而Judy还没有到.
例∶6) I am starting.Is the dinner ready yet?我肚子饿,晚餐准备好了吗?
例∶7) I do not know which company I am going to work yet.我还不知道我要去那一间公司上班.
例∶8) They have not arrived yet.他们还没有到.
注∶yet词通常与Present Perfect Tense（has,have+第三动词,到目前为止的表达动词的用法）有密切的关系.
Still和yet的分别
Still：I called her 2 hours ago but she still hasn’t arrived.我两个小时前有拨电给她,她还是没有到.（她本来早就应该到了）
Yet：I called her 2 hours ago but she hasn’t arrived yet.我两个小时前有电话给她,她还是没到.（我预了她,可是她还没有到）
Already已经
Already这个词是放在句子的中间.这个词的意思是已经做了.Already是用在正句（Positive Sentences）
例∶9) Jolin has already done her work Jolin.已经做完她的工作.
例∶10) Shall we eat lunch?I am already hungry.我们去吃午餐好吗?我已经肚子饿了.
例∶11) We have already changed the project.我们已经换了那个计划.
例∶12) Kelvin and Cheng have already done their work.Kelvin和Cheng已经做完他们的工作.
记得∶Already通常与Present Perfect Tense有关.
Present Perfect Tense（到目前内止动词的表达）