写出一个有一根为2的一元二次方程( )。
(答案不唯一)
As many as five courses are provided,and you are free to choose ________ suits you best. (2012·陕西,20)
A.whatever
B.whichever
C.whenever
D.wherever
新鲜水果常用保鲜袋包起来,目的是
A.防止虫蛀
B.降低蒸腾作用
C.降低呼吸作用
D.保持水果细胞生活的适宜温度