________ hard is the key to success. 
#51086
A
To work
B
Work
C
Worked
D
Works
推荐题目
They are looking forward to _______Beijing.
#50747
A
visit
B
visited
C
visits
D
visiting
—Would you mind _______ in the classroom?—Sorry, I won’t do that again. 
#49774
A
not running
B
don’t run
C
not to run
D
to not run
— I tried       it out in this way, but I failed.— Why not       it in some other ways?
#50281
A
to work; try doing
B
to work; try to do
C
working; try to do
D
to work; to try doing