A:1
B:2
C:3
D:2
____Six.
____I have computer class, PE and science.
____How many classes do you have on Wednesdays?
____Is it Wednesday today?
____What do you have in the afternoon?
____Yes, it is.
A CO2 B CO C N2 D____.
设数列an的前n项和Sn=n2,则a8的值为( )
失去了规则,人们的权利就无从保障,人们的自由就会遭到侵害。可以说,规则的存在最终保障了人们的权利和自由。( )