if引导从句

sentence:
  I see/I agree/Hold on/No way/So long/Not bad/Why not?
  I quit/Be quiet/Allow me/Let go/Have fun/Good job/Shut up
  Where r u headed?
  How can I get in touch with u?
  It is my treat this time.
  Where can I wash my hand?

key words and expressions:
   obey          遵守,服从                   reminder        提醒的人,提示
   park          停放                            fail            无视,忘记
   give a ticket 得到一张罚单          give sb. a ticket for speeding 
   No parking    不能停车               No admittance    不得入内
   No cycling    不准骑单车            contrary         相反的,反面
   quite the contrary  正好相反        fun              好玩的,娱乐
   can(could) not fail to    不能做某事,忘记做某事
   entertain     娱乐,款待,招待      volunteer        志愿者

Pattern:
   She fails to come..
   He never fails to write his father every week..
   She can not fail to recognize me.

Syntax:
   if引导的条件状语从句
   主句一般现在时,从句一般将来时..
   If u receive a request like this,u can not fail to obey it.
   U will enjoy your stay here if u pay attention to our street signs.