Though many extra planes and trains are used to carry passengers, traffic tools are still _____needed during “May Day” holidays [ ]

We surely desire that the tour leader ________us immediately of any change in the travel schedules.

You can’t complain about being left out ______you don’t make any effort to share your joys and sorrows with others.

I heard the voice, I knew that my father was coming.[ ]

More people are choosing to work _____ retirement age，since the living expenses are shooting up sharply.