The president _____ the new economic policy. [ ]

They are leaving for Hangzhou in ten days — ________, next Friday

Look! A man is cutting a tree on the moon. –It ______be true. The teacher said there is no air on the moon.

He had to pause from time to time to wipe the sweat from his forehead, because the air-conditioning system _________.

The computer was one of the greatest______ in the 20th century.