题目

—Could you tell me___________?— The Sahara. It's about 9,00,00 square kilometers in size.A.how large is the Sahara B.what was the largest desert C.what the largest desert is 答案：【答案】C【解析】句意：——你能告诉我最大的沙漠是什么吗？——撒哈拉沙漠。它大约有90000平方公里。考查宾语从句。how large is the Sahara撒哈拉沙漠多大，疑问语序；what was the largest desert最大的沙漠是什么，疑问语序；what the largest desert is最大的沙漠是什么，陈述语序。根据语境可知，空处是宾语从已知一元二次方程x2-6x-5=0两根为a、b，则+的值是    ；已知y=+5，则=    ．