税务机关收到税款后，应当向纳税人开具完税凭证。纳税人通过银行缴纳税款的，税务机关可以委托银行开具完税凭证。
参考答案：对
This question is ______ easy, all the students can answer the question.[ ]
A. too much
B. too many
C. much too
D. many too
中枢免疫器官为（）
A.胸腺和淋巴结
B.脾脏和胸腺
C.淋巴结和脾脏
D.胸腺和骨髓
E.黏膜免疫系统
