具有叶鞘的科是：
A．姜科
B．天南星科
C．百合科
D．薯蓣科
E．禾本科泽泻科
参考答案：A,B,E
. It’s illegal for anyone under 21 in the USA, the highest drinking age in the world to buy alcohol, and stores or restaurants caught alcohol to people under the legal age will involve
their licenses.
A．to sell; to lose
B．to sell, losing
C．selling; losing
D．sold; lost
龈下刮治放入器械时，工作端平面与牙根面之间的最佳角度是
A．0°B．90°C．40°D．80°E．110°
