把16g氧气和12g碳放在密闭的容器里，在一定条件下充分反应，最终密闭容器中有[ ]
A.
B.
C.
D.
答案：C
It is his great pleasure to be ____________ with the highest reward by the president.
A．provide
B．presented
C．made
D．represented
导致胃酸分泌的内源性物质是（）
A．肾上腺素
B．ACh
C．去甲肾上腺素
D．肽类物质
