在298K，1.01×105pa时，2molH2(g)燃烧生成水蒸气放出热量48

"士别三日，即更刮目相待。"这句话告诉我们（）

睾丸和卵巢分别是男女最主要的生殖器官，是因为[ ]

A．他们能产生生殖细胞

B．它们能产生生殖细胞和分泌性激素

C．它们能分泌性激素

D．它们能分别分泌雄性激素和雌性激素

《中 * * 关于全面深化改革若干重大问题的决定》提出加快自由贸易区建设的主要理念是？

空间点阵

Which of the following statements is true of futures contracts()

A. All futures contracts are bought and sold on organized exchanges and the terms of futures contracts are determined by the buyers and sellers themselves. 

B. The Clearinghouse serves to guarantee the performance of all parties to futures contracts. 

C. Both are true.