These last 22 years have really been amazing, every prediction we've made about improvements have all______.

A．come over

B．come clown

C．come along

D．come true

生素C理化性质的特点之一为（）。

A.遇光照稳定，不易破坏

B.在空气中不易被氧化

C.碱性环境不易破坏

D.有铜、铁等金属存在时容易氧化