具有杀虫功效的药物是
A．白及B．仙鹤草C．棕榈炭D．血余炭E．炮姜
参考答案：B
The more one is _______ the English-speaking environment, the better he or she will learn the language.
A．filled in
B．exposed to
C．caught on
D．kept up
50岁以上中、老年人便血，应考虑是（）
A.肠息肉
B.直肠癌
C.肠套叠
D.小肠结核
E.粘连性肠梗阻
