________ 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 his dad died, he felt ________his whole world was hopeless .
#31412
A
in case
B
as though
C
so that
D
even though
The fact that smoking is harmful to health is__________ most smokers admit．
#32340
A
what
B
whether
C
where
D
that
__ __ many Chinese women have received higher education, there are still obstacles that prevent them from enjoying the same opportunities for education and employment as men．
#33681
A
Whether
B
Because
C
When
D
Although
Please do me a favor-----_________ a seat for me in case the hall is too crowded.
#31636
A
to save
B
saving
C
save
D
saved