The research mainly deals with the diffi
题型:选择题
问题:
The research mainly deals with the difficulty the students have ________ their attention on their
study all the time. [ ]
A. to focus
B. to be focused
C. focusing
D. focused
The research mainly deals with the difficulty the students have ________ their attention on their
study all the time. [ ]
A. to focus
B. to be focused
C. focusing
D. focused