________ he found the idea interesting, it was too difficult to be of practical use.
#29985
A
While
B
Once
C
If
D
Until
推荐题目
I wrote to my parents once a week,____ I was too busy with my teaching work.
#80142
A
it
B
unless
C
when
D
as
Hard _____ he tried, he failed to catch up with the first runner.
#32786
A
although
B
as
C
while
D
when
____________ many times, but he still couldn’t understand it.
#32349
A
Though he had been told
B
Having been told
C
Having told
D
He had been told