几道英语选择题``麻烦回答一下

几道英语选择题``麻烦回答一下
1.Put ( )that knife before you hurt somebody.
a.on b.down c.up
2.He spent the whole day in the mountains and didn't get( )till dark.
a.back b.in c.up
3.They are putting( )several new houses on our street.
a.down b.up c.on
4.I have a good ( )when I was a child.
a.day b.hour c.time
5.The last guests to reach the hotel checked ( )at twelve o'clock.
a.out b.in c.off