Whenaspacecrafttravels,oneofthemajorproblemsisreentryintotheEarth’s_______.
All the memories of his childhood had _______ from his mind by the time he was 65.
In the United States, the foreign policy is decided by the ________ government, not by each state.
As a teacher, you should not _______ the students from asking questions in class.
The _______ work continued for more than a week but there was still no sign of the missing boy.