This boy is Peter .He is from America.He is ten years old . His hair is yellow.Peter can play basketball. This is his school.It's very big. There are forty students in his class. Miss White is his English teacher. Peter is good at English.
某同学用显微镜观察时,若目镜为5×,物镜为10×,则物像的放大倍数是( )
在三棱柱ABC﹣A1B1C1中,侧面ABB1A1为矩形,AB=2,AA1=22,D是AA1的中点,BD与AB1交于点O,且CO⊥ABB1A1平面.
证明:BC⊥AB1
把木炭加热至红热,投入到浓硝酸溶液中,产生NO2、CO2两种气体组成的混合气体X,用X作如下图所示的实验:
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