Ⅰ.单句语法填空：根据句意，在空线处填上适当的代词。
1．(2019·天津市东丽区高三毕业班质量监测)I was going to pay by cash when it suddenly occurred to ________ (I) that I had left my purse at home.
答案：me 这里to是介词，设空处作介词的宾语，所以后面接宾格形式，故填me。
2．(2019·河南豫北名校联考)It is especially effective at ridding bacteria of your teeth and keep ________ healthy!
答案：them 这里指代前面的复数名词teeth，用宾格代词them作keep的宾语。
3．(2019·湖南湘潭高三上学期一模)The zoo began in the 1860s, making ________ the first official zoo to open in New York.
答案：it 设空处指代上文的the zoo，作making的宾语。
4．(2019·云南师大附中月考)The difference between a man who succeeds and ________ who does not lies only in the way each treats opportunities.
答案：one 此处用one表泛指，表示与前面提到的a man为同类但并非同一个。
