6.You _____ pay too much attention to your reading and listening skill, for they are of great importance.
To battle world hunger, the great scientist once traveled to many places where populations _______ faster than crop production at that time.
The government won’t have the public officials ___ asking for gifts or money from people.
Unfortunately, some natural signs which might have helped more people survive the earthquake were ________.
. ___________ the extreme levels of air pollution, city authorities have started to take measures to quickly reduce pollution levels and protect city dwellers.
Whenever I read the old letters, _____ was fairly often, sweet memories warmed my heart.