________ several times，but he still doesn't know how to do it correctly.
#30467
A
Although I've taught him
B
I've taught him
C
Having been taught
D
Having taught
推荐题目
—When will the visas be ready, sir? — everything goes well, you should get them in 14 workdays.
#30790
A
Although
B
As far as
C
Unless
D
As long as
Sherry is in good shape physically _____ she doesn’t do enough sports.
#31292
A
if
B
even though
C
unless
D
as long as
Many teenagers say that _____ they have a lot of friends, they really have no best friend.
#32317
A
when
B
while
C
if
D
because
In the final exam of last term, our maths teacher Mr.Wu gave us ________we all couldn’t work out .
#33849
A
such a difficult problem that
B
so a difficult problem as
C
so difficult a problem that
D
as difficult a problem as