——Jane Zhang is going to hold a concert here in July. ——Really? ________ exciting news!
A:How
B:What an
C:What
两个等差数列{an}和{bn},其前n项和分别为Sn,Tn,且 SnTn=7n+2n+3 ,则 a2+a20b7+b15 等于( )