— Where 's your mother ?— She ________ Shanghai . She won't be back ________ next week .
A:has gone to, until
B:has been to, until
C:has been to ,after
D:has gone to, after
已知25℃时,Ksp(AgCl)=1.8×10﹣10,Ksp(Ag2S)=6.3×10﹣50.下列说法正确的是( )
读图回答下列问题。