(2) Alex and Paul (
) each other since high school.
A. are known
B. have been known C. have known
D. are knowing
(3) I was (
)for support by the teacher.
A. called on
B. be called on
C. calling on
D. to call on
(4) Knowing is one thing and teaching is (
A. others
B. the other
C. another
D. the others
(5) You(
) be late for the class because punctuality is important.
A, had better to not B. not had better
C. had better not to
D. had better not