We _________ last night, but we went to the concert instead.
—Your suitcase seems very heavy. Need any help?—__________.
A common memory they all have ______ their school days is the school uniform.
Every 40 minutes we will take a 20-minute break, ______ your guide will give a short talk on different aspect of the Great Wall.
Languages across the world are becoming extinct ______ endangered mammals and four times endangered birds.
As a Chinese saying goes, a mountain ______ be too high or an ocean too deep. Therefore, there is no end to our self-improvement.