题目

Keep your child off drugs,  ________ it will ________ many serious health and behavior problems.     A. or; point to   B. or; lead to   C. and; point to   D. and; lead to 答案：B   △ABC中，∠C=90°，点O为△ABC三条角平分线的交点，OD⊥BC于D，OE⊥AC于E，OF⊥AB于F，且AB=10cm，BC=8cm，AC=6cm，则点O到三边AB、AC、BC的距离为（　　）A．2cm，2cm，2cmB．3cm，3cm，3cmC．4cm，4cm，4cmD．2cm，3cm，5cm