i must lerned about english改为什么？(只改must)

英语提问(初二）
（ ）1.Zhou Feng has lerned English for many years ,but he can ____understand the English speakers.
A.hardly B.certainly C.always D.almost
( )2.Most of my students don't like to talk to their parents,but I am _____them.
A.different from B.surprised at C.the same as
( )3.--Ms Lin is very popualar among the students.
--Yes.Her classes are ____lively and interesting.
A.always B.sometimes C.hardly D.never

解释两个句子
It was five years since I lerned English.
和It was five years since I began to learn English.
这两句怎么区别?给点相关句型的解析!