/ / and / i: / are the most frequently used vowels in the weak forms of function words.（）

The arbitrary nature of language is absolute, i.e., the...

判断题The arbitrary nature of language is absolute, i.e., there are no words in world languages that maintain a correspondence between form and sound.（）

单句改错Believe it or not! The new train can travel at a sp...

未知题型单句改错Believe it or not! The new train can travel at a speed of sound.单句改错 Believe it or not! The new train can travel at a speed of sound.

I hope you can come back safe and sound. _____________

未知题型I hope you can come back safe and sound. _____________