They are so busy that they have no time to do any sports, ______they need to do so.

It ___________last night, for the ground is wet outside.

This nationwide smog should serve as a reminder to all, indicating a high time that we ______ on what we’ve done to the environment.

lege, Barack Obama didn’t know that he the first black president of the United States of America.

Susan is taller than ______________ in her class.