Think and write. 根据要求写字母或单词。7%(1)Canada→CAN (照例写) China→___________(2)let us(缩写形式) ____________(3)isn’t (完全形式) ____________(4)swim(doing形式) ____________(5)by (同音词) _________(6)big (形容词比较级) ____________(7)old (2个反义词) ________