砂仁的显微特征是：（）
A.假种皮
B.色素细胞
C.油细胞
D.石细胞
E.内胚乳、糊粉粒
参考答案：A, B, C, D, E
客户对其所获得商品的"利用可能性"等于存货服务率与配送服务率的乘积。
--These days I can only sleep for four or five hours at night as I’m too busy with my research work.
--If you keep going on like that, you are sure to ______ sooner or later.
A．break down
B．get down
C．calm down
D．put down
