In developed countries, before toxic chemicals are released into rivers and lakes; they should be treated in order to avoid ______.

A．Talk to his sister.
B．Look at a map.
C．Go on a diet.
D．Tell the man why.

A．The woman has passed her final exams.
B．The woman wants to know how to write term papers.
C．The woman is going to visit Gettysburg.
D．The man introduces his experiences in Gettysburg.