John as well as the other children who _______ no parents ______ good care of in the village.
A:have; is being taken
B:have; has taken
C:has; is taken
D:has; have been taken
①求水的体积V水。
②求水对容器底部的压力F水。
③若圆柱体乙的体积为V乙,密度为2ρ水,现将其沿水平方向截去一部分,并将截去部分浸没在甲容器的水中(水不溢出),使水对容器底部压力的增加△F水等于乙剩余部分对地面的压力F乙’,求乙截去的体积△V。(用字母表示)
有关生态系统的叙述中,正确的是( )
关于海陆分布的叙述,正确的是( )