________ 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
The little girl who got lost decided to remain _________she was and wait tor her mother.
#80594
A
where
B
what
C
how
D
who
_____, experts point out that students can easily fail at starting their business because of a lack of preparations.
#80650
A
But
B
However
C
while
D
though
__ You keep on coughing．What’s the matter? __ Oh, I’ve got a cold．Nothing serious, ______?
#33622
A
yet
B
though
C
indeed
D
anyway
I really wonder ______ he has posted me many parcels _____ we worked together .
#80505
A
how ; after
B
why ; when
C
when ; before
D
why ; since