1．--What on earth are the police busy with?
---They have been looking into how the plane crash _______.
A. came out B. came up C. came down D. came about
2．---What ____ the population of China ?
---China has a population of 1.3 ____.
A. is, billions B. are; billions C. is; billion D. are; billion
3．______ to collage this year, We must study harder than ever before .
A. Go B. Going C. Gone D. To go
