________ many times，I still didn't know how to operate the machine.
#91844
A
Having taught
B
Having been taught
C
Being taught
D
Teaching
推荐题目
Laura was away in Paris for over a week.When she got home，there was a pile of mail________for her. (2013·辽宁，28)
#88736
A
waited
B
to wait
C
waiting
D
was waiting
_ properly, a car can be used for many years.
#90465
A
Maintained
B
Maintaining
C
To be maintained
D
To maintain
To avoid _________ on how to operate the machine, you should first read theinstructions carefully.
#93839
A
to get confused
B
getting confused
C
to get confusing
D
getting confusing
We shouldn’t complain about________, because many families are much _____ in the mountainous area.
#96857
A
being poor; worse off
B
being rich; better off
C
to be poor; badly off
D
to be rich; well off