I want to know if Maria ______ us in the fashion show tonight.—I believe if she ______ her homework, she will join us.

Some steps have been taken to protect the forest _______.

The CDs are on sale！Buy one and you get ______completely free.

We live in an age _____ more information is available with greater ease than ever before.

Oil prices have risen by 32 percent since the start of the year, ____ a record US$57,65 a barrel on April 4. [ ]