A:behind Tony
B:on Tony's right
C:in front of Tony
看图,读一读,选择句子补全对话。
Lily: Good afternoon, Mum. I'm home.
Mum: ____ How are you today?
Lily:____ It's very hot today.
Mum: Have a pear, Lily.
Lily: ____
Mum: Taste it. ____
Lily: It's sweet and juicy.
Mum: ____
Lily: Yes, I do.
现有圆心角为 2π3 ,弦长等于2 3 米的弧田.
(I)计算弧田的实际面积;
(II)按照《九章算术》中弧田面积的经验公式计算所得结果与(I)中计算的弧田实际面积相差多少平方米?(取π近似值为3, 3 近似值为1.7)
在电能输送的过程中,如果输送的电功率一定,将输电电压升到原来的10倍,则输电线上损失的功率将变为原来的 ____ 倍,由此可见,若想有效的减小电能在输电线路上的损失应采用 ____(选填“高压”或“低压”)输电.