中国革命的首要问题是（）。
A、阶级斗争
B、分清敌友
C、制定纲领
D、建立政党
参考答案：B
淀粉能够在人的口腔中转变为糖，是因为人的唾液中含有（ ）
A．水
B．酶
C．淀粉
D．糖
Which of the following statements about Langerhans’ cells is TRUE
A．They commonly are found in the dermis
B．They function as sensory mechanoreceptors
C．They function as receptors for cold
D．They play an immunologic role in the skin
E． They are of epithelial origin
