— Sammy, do you like the grammar book?
—Oh, I love it very much because it is so practical.
A:interesting
B:perfect
C:useful
在草原上,夏季雨量充沛时草很茂盛,野兔数量增加,草被吃掉过多,但过一段时间,野兔的数量又会下降,草又多了起来,这是因为( )
用下列词语造句
①勇敢
②狡猾