题目

---I think students should be allowed ___ homework with friends.   ---I disagree. They talk instead of ________ homework. A. do, doing       B. to do, to do       C. to do, doing        D. doing, to do 答案：C1、下列各项不属于生物防治的是（   ） A．狮吃羚羊                                 B．周氏啮小蜂将卵产在美国白蛾的幼虫体内 C．引入青蛙消灭蝗虫                         D．七星瓢虫吃蚜虫