- _____you sing English songs yesterday?
- No,I didn't. ( )
A:Do
B:Did
C:Will
下列模拟掷硬币的实验不正确的是( )
1)f(x)=2axg(x),(a>0,a≠1);
2)g(x)≠0;
3)f(x)g′(x)<f′(x)g(x)且 f(1)g(1) + f(−1)g(−1) =5,则a=____.
读亚洲气候类型图,图中表现出亚洲的气候特征有( )