While building a tunnel through the mountains, ______.
#93626
A
an underground lake was discovered
B
there was an underground lake discovered
C
a lake was discovered underground
D
the workers discovered an underground lake
推荐题目
He said while ______ in the countryside, he ______ a lot of hardships and of course learned a lot.
#92795
A
worked, got through
B
working, went through
C
was working, experienced
D
has worked, experienced
 I'm busy now. I'm sorry I can't help ____ the flowers. 
#98051
A
watering
B
watered
C
waters
D
to water