____ Helen’s knowledge and vocabulary expanded, she asked more and more questions. 
#31493
A
When
B
While
C
As
D
Before
推荐题目
________ in his book, he didn't notice me ________ I entered the room.
#29957
A
Devoted; when
B
Absorbed; while
C
Absorbed; when
D
Devoted; while
__________ he took part in the competition, he won a second prize. 
#33676
A
The first time
B
For the first time
C
At a time
D
At one time