—Tom is never late for work. Why is he absent today?—Something _______to him.
A. must happen
B. should have happened
C. could have happened
D. must have happened
查看答案
最小的语音单位是
A. 音素
B. 音节
C. 音位
D. 声母
汉语拼音方案中的声母有多少个?
A. 20
B. 21
C. 23
D. 26
a和e读音不同,主要是因其( )不同。
A. 音高
B. 音长
C. 音强
D. 音色
xian由几个音素组成?
A. 1
B. 2
C. 3
D. 4