By the time Billy was 6, he in the sea.
#101498
A
had already swum
B
was already swimming
C
has already swum
D
already swam
推荐题目
--- Jack, what about the lecture? --- It is the most inspiring lecture that I _________ since I came to this university.
#99803
A
attended
B
have attended
C
am attending
D
had attended
________ a certain doubt among the people as to the practical value of the project.
#99564
A
It has
B
They have
C
It remains
D
There remains
With the rapid development of medical science, we ___ more new drugs used in the treatment of cancer．
#100437
A
see
B
had seen
C
will be seeing
D
would see
He ＿＿＿articles for our wall-newspaper these three years, and he ＿＿＿about forty articles.
#104632
A
has been writing； has written
B
has been writing； wrote
C
is writing； has been writing
D
has written； has written
We were listening closely to the lecture yesterday evening when suddenly the light _______.
#102340
A
had been gone out
B
was going out
C
was gone out
D
went out