Might- 50% or less likely that something takes place.
Could- stating a possibility
Must- 90% certain that something takes place.
Should- giving advice
A modal in perfect form makes a statement about something in the past.
Cell phone calls from students hiding in and around Columbine High School, which Dylan and Eric could have used to pinpoint the locations of their intended victims.
This is in reference to a possible action in the past that was not taken.
Rules
1. "Have" + past participle as a modal perfect doesn't carry the same meaning as the present perfect tense. It simply indicates past time.
2. The past form of should is use to give "hindsight advice". For example:
When I look back at my past, I realize that I was not a good student. It would have been better if I was a good student. Therefore:
I should studied harder when I was in high school.
http://daniel-j-stone.blogspot.com (C) 2009-10
No comments:
Post a Comment