We often start our class ______ a song. [ ]
A. in
B. for
C. by
D. with
答案:D
造成反应器压力波动的原因有哪些?
下列哪一项是以非交易关系为内容的合同()
A、物权合同
B、债权合同
C、知识产权合同
D、收养合同