On July 20, 1969, Neil Armstrong become the first man _________foot on the moon .
I find painting and listening to music __________.
—I usually go there by train.—Why not __________ by boat for a change?
Having been ill in bed for nearly a month, he had problems __________ the exam.
It was so dark that he __________.
The Wangs are considering __________ to Huangshan for a trip at five tomorrow morning.