Solution: Had better

แบบฝึกหัดนี้คงจะไม่ยากเกินไปใช่ไหม :)

• You should have locked the door before you set out.
  It would have been better if you had locked the door before you set out.
  
  
• You should go to bed as we have to be up early tomorrow.
  You had better go to bed as we have to be up early tomorrow.
  
  
• You should have asked her opinion before making a decision.
  It would have been better if you had asked her opinion before making a decision.