题目

下列为蝗虫的发育过程是（ ）①成虫 ②蛹 ③受精卵 ④幼虫． A . ①﹣②﹣③﹣④ B . ③﹣④﹣① C . ③﹣④﹣②﹣① D . ③﹣②﹣① 答案：B4. The costs were (减少) by 20% last year and it was a great success.