He had lost track of his daughter for 24 hours — he was very concerned（ ）her safety.
A.正确答案Aabout
B.in
C.with
D.into
He had lost track of his daughter for 24 hours — he was very concerned（ ）her safety.
He had lost track of his daughter for 24 hours — he was very concerned（ ）her safety.
A.正确答案Aabout
B.in
C.with
D.into
