Our teacher told us light (光) _________ much faster than sound .
Environment(环境) is very________,but you don’t understand the_______ of it,you always drop litter everywhere.
He spent as much money as he could _______ a new iphone6.
The teacher told me _________when I left the classroom.
There ______ a large number of students in our school. The number of the students _______ over three thousand.
There is a test tomorrow. So Tom is busy _______ for it.