—Be careful! You might fall into the water. 

—Thank you. I ______ I _______ so close to the pool.

A．didn’t know; am standing

B．don’t know; am standing

C．didn’t know; was standing

D．didn’t know; would stand

关于血管的止血机制说法不正确的是（）

A.血管损伤后立即收缩止血

B.释放vwF促进血小板聚集

C.内皮释放TF启动内源性凝血

D.基底胶原暴露激活FⅫ

E.释放ET增强血管收缩