题目内容
He has worked ________ this maths problem for an hour but he hasn't worked ________.
[ ]
A.on, out it
B.out, on it
C.for, at it
D.on, it out
答案:D
练习册系列答案
相关题目
题目内容
He has worked ________ this maths problem for an hour but he hasn't worked ________.
A.on, out it
B.out, on it
C.for, at it
D.on, it out