判断对错．
扇形统计图能反映数据的变化趋势．
发达国家主要分布在 ( )
根据短文理解选择答案。
FILA Men's T-shirts
Made in: China
Colour: white
Size: M
Material: cotton
Wash them with warm water in machines (洗衣机).
Price: ￥320
FIRS Men's Coats
Colour: grey
Size: L
Material: 98% wool, 2% cotton
Dry cleaning (干洗) only.
Keep them in dry and cool places.
Price: ￥1320
Senda Women's Shoes
Colour: pink
Size: M (235 mm)
Material: leather
Keep away from water.
Price: ￥820
①原溶液加过量的NaOH溶液，产生白色沉淀；
②原溶液中加BaCl2溶液不产生沉淀；
③原溶液中加AgNO3溶液产生白色沉淀，再加稀硝酸白色沉淀不溶解，回答下列问题：
