不属于诗意人生作品是（） A.饮酒（其五） B.赤壁赋 C.至乐 D.陶然亭的雪

The rate of racial progress varies in different areas of the country, but in the past ten years _________ more improvement.

A．there is

B．it is

C．there have been

D．there has been

铸坯内部化学成分和杂质分布不均匀的现象叫（）。

水分子之间是通过（）相互缔合的。