________ 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
She had a tense expression on her face, ______she were expecting trouble.
#34112
A
even though
B
as though
C
now that
D
in case
______ it is required to follow the grammatical ruled when witting English,there are always some exceptions.
#80527
A
Unless
B
while
C
As
D
Since
Many experts hold the view _______ protection awareness is _______ the key to better environment lies.
#33748
A
that; where
B
which; in which
C
which; where
D
that; in which
It is five years ____ he lived here.In other words, he left here five years ago.
#80519
A
before
B
since
C
that
D
when
He made a mistake, but then he corrected the situation ________ it got worse.
#32998
A
until
B
when
C
before
D
as