单项选择题

What is a by-product of burned coal（）

A．Aluminum, silicon, and magnetic.
B．Paving material.
C．Fly ash.
D．Concrete additiv

<上一题目录下一题>

热门试题

单项选择题

What was Helen Keller like when Miss Sullivan met her（）

A．She was quiet and shy.
B．She was bright and friendly.
C．She was weak from illness.
D．She was uncontrollabl

单项选择题

Which of the following statements can best be inferred from the passage（）

A．Fishes only "speak" to communicate with each other.
B．Researches are now being made to study the significance of fish sounds.
C．Sea animals have a sharper hearing ability than men.
D．Sounds made by fish cannot be transmitted through the air.