优题课 - 聚名师,上好课(www.youtike.com)
  首页 / 试题 / 高中英语 / 试题详细
  • 科目:英语
  • 题型:单选题
  • 难度:中等
  • 人气:498

A new technique ____ out, the yields (收成) increased by 20% .

A.having working B.having been working
C.has worked D.had been worked
登录免费查看答案和解析

Anewtechniqueout,theyields(收成)