A:20°
B:50°
C:70°
D:30°
Before I watched ____ 3-D film Life of Pi, I had never seen ______ wonderful film like this.
在路边安装电线杆,每两根电线杆之间相距10米,从第一根到最后一根电线杆一共长100米,一共安装了多少?( )
A种植物细胞(基因型为Aa),B种植物细胞(基因型为Bb);去掉细胞壁后,诱导两种体细胞的原生质体融合,形成单核的杂种细胞。若经过组织培养得到的杂种植株是( )
( I)求数列{an},{bn}的通项公式;
( II)设cn=an•bn,求数列{cn}的前n项和Cn.