在土地上连续耕种，使土地得不到____ ，土壤____ 逐渐下降。
He fell off the bike and hurt his leg yesterday._______, he had to stay at home for two or three months.
如图曲线I表示黄豆光合作用速率与光照强度的关系（温度适宜、CO2浓度为0.03%）．在y点时改变某条件，曲线变为Ⅱ．下列分析合理的是（ ）
—Where is Mrs. Smith?
—She isn't here. She ________ to England.
是R上的偶函数，且在区间
上是增函数.
，则( )