Sir.You should ___the letter.A.post B.have posted该选哪个答案?

Sir.You should ___the letter.A.post B.have posted该选哪个答案? I have never dined with you,sir;and I see no reason___I should now.1.how2.why3.which意思,为什么? I've never dined with you,sir; and I see no reason why I should know.请翻译这个句子. What would you like,sir?________ _______ you ________,sir? May I help You,sir 改为( )I ( )you,sir Can I help you,Sir? --Would you like ___ ,sir? can i heip you,sir? may i help you sir? Excuse me,sir.Could you please tell me what number I should dial to get the （ ）A.throatB.verseC.conductorD.operator ---Sorry,Sir I forgot to do my homework last night.---Tom,you____many times,You should believableA.forgot B.forgrt C.had forgotten D.have forgotten Can I help you sir 怎么读 what can i do for you ,sir What other would you like,sir?改错 You should you should should you 还是 you should Sir,you should ______at the red light.But you did't.A.stop B.have stopped C.not have stopped D.have to wait小弟愚笨,请诸位高手再帮忙解释下各个选项,