—I have done well in the exam because of no careless mistakes. —Congratulations! Students can never be _______ careful in exams. A. so B. very C. too D. enough 答案:C
15.低磷酸酯酶症是一种遗传病,一对夫妇均正常,他们的父母也都正常,但丈夫的妹妹和妻子的哥哥患有低磷酸酯酶症,这对夫妇生患病儿子的概率是 A.1/3 B.1/18 C.1/8 D.5/24