I'd like to ask about the use of "had better". Is it alright to use it this way?
A student says to his teacher
"Mr. Brown, you'd better take your umbrella with you. It's going to rain."
(NOT a teacher) Yes, it is ALL RIGHT to use it that way. Here in the States, many native speakers even leave out the "had" in fast conversation: You better take your umbrella. (P.S. Please be careful when you use "had better." Sometimes it is a threat: You had better not bother me, or I'm going to hit you.)