The students were talking and laughing（ ）the teacher came in.
A.
while
B.
after
C.
since
D.
when
正确答案是D
The students were talking and laughing（ ）the teacher came in.
The students were talking and laughing（ ）the teacher came in.
A.
while
B.
after
C.
since
D.
when
正确答案是D