由6个百、3个十、2个一组成的数是____;
由5个百和9个十组成的数是____
一 I have made great progress in spoken English since last year.
一 Well done! I am sure you'll be good at it soon.
切西瓜时会流出许多汁水,这些汁水是西瓜细胞的( )
根据入射光线和折射光线,在图中的虚线框内画出适当的透镜。