Helen is my friend. She is thirteen years old. She is ____ (study) in London, the capital city of England. She'd like to visit different ____ (place) and meet different ____ (people) when she is on holiday. She likes reading very much. Now, she's standing ____ (介词) line in a bookshop. She's buying ____ (冠词) English storybook.

台湾省的主要少数民族是（　　）

原始生命的起源过程中，从无机小分子物质生成有机小分子物质的场所是（   ）

如图，是某同学在上学路上的情景，由于风大伞被吹得向上翻起，伞向上翻是由于伞的下表面风速比上表面的风速____，从而使伞的下表面受到空气压强比上表面大所致．学生背的书包，书包带通常都比较宽大，这有助于减小书包对肩膀的____．

点$P(2,-1)$为圆$(x-1{)}^2+y^2=25$的弦AB的中点,则直线AB的方程为   （）