(2013·凉山一模)Life is like riding a bicycle. ________ your balance, you must keep moving.
#89279
A
Keeping
B
To keep
C
Keep
D
Being kept
推荐题目
    around the lab, we were taken to see the library.
#95015
A
Being shown
B
Showing
C
Having been shown
D
To show
 The tower_____ in the 1800s is the oldest building in this area.
#90031
A
to be completed
B
being completed
C
completed
D
Completing