—Many people are suffering from the earthquake.
—I see. Food and clothes should be sent to them .
A:on purpose
B:at present
C:right away
D:ever since
已知Sn为等差数列an的前n项和,若S1=1,S4S2=4,则S6S4的值为( )
新中国成立以来的宣传画折射出时代的变迁。对下面的宣传画所反映的时代特征描述正确的是( )