A. I spent two hours there.
B. He is Yang Liwei.
C. I went to my friend's house.
D. I was born in 2004.
E. No, I didn't.
点P(﹣1,2)关于y轴对称点的坐标是( )
从亲代到生殖细胞再到子代,染色体数量的传递规律是( )
如图,在梯形ABCD中,DC∥AB,AD=BC,BD平分∠ABC,∠A=60°.过点D作DE⊥AB,过点C作CF⊥BD,垂足分别为E、F,连接EF,求证:△DEF为等边三角形.
一凸透镜的焦距是50cm,则用该透镜制作的眼镜的度数是____ .
有理数﹣2012的相反数是( )