低产水稻土一般都有()土层。
参考答案:潜育化
Mr. Reed made up his mind to devote all he had to ________ some schools for poor children.
A.set up
B.setting up
C.have set up
D.having set up
某个地区某个年份人口死亡率骤然升高,产生这一现象的原因可能是[ ]
A、环境污染比较严重
B、医疗卫生条件下降
C、经济发展速度减慢
D、遭遇大的自然灾害