_______ I walked into class, the teacher had started teaching already.
A：By the time
B：While
C：After
D：Because
儒家学派对我国思想文化产生了深远影响，其创始人是（ ）
– People all over the world do something good for the earth on April 22nd –– Earth Day.– Well. ______ what we should do is to make every day Earth Day.
