问题
Once a reporter receives his assignment from the chief-editor, he has to ______ on his work and tries his best to work on it until the chief-editor ______ it.[ ]
A: fix his attention; approves
B: focus; proves of
C: concentrate; approves of
D: get down; approves
B: focus; proves of
C: concentrate; approves of
D: get down; approves
正确答案是：
