如果人的头颅直径为 20 cm，具有衍射作用的声音频率为
A、频率大于2500Hz的声音；D
暂无解析
After some very trifling stupid ______, she ventured to ask whether it was true that he was going away.
This is ________ good reading habits are not only an important study skill for the student, but also an important life skill for anyone.
“我们党所办的报纸，我们党所进行的一切宣传工作，都应当是生动的，鲜明的，尖锐的，毫不吞吞吐吐。”这一观点出自
The long prison galleries were full of life and ________ grave bustle.
In 1995,an average of _______ of domestic travelers went on sightseeing in China.
