题目

按要求变换下列句型。 1. They have ever been to an English-speaking country. (一般疑问句) ______________ they ever ______________ to an English-speaking country . 2. She has been a flight attendant for two years.(对划线部分提问) _______________________ she ________________ a flight attendant. 3. His father has been to America twice.(对划线部分提问) _______________________ has his father __________________ to America? 4. Linda is taller than any other girl in her class. ( 同义句) Linda is __________________________ girl in her class. 5. improve , why , you用10mL的0.1mol/L溶液恰好可使同体积的硫酸铁、硫酸锌、硫酸钾三种溶液中的硫酸根离子完全转化为硫酸钡沉淀，则三种硫酸盐溶液的浓度比是 [　　] A．3∶2∶2 B．1∶2∶3 C．1∶3∶3 D．3∶1∶1