正常足月妊娠,子宫腔容量平均比未孕时增加
A. 100
B. 300
C. 500
D. 800
E. 1000
What are the letter or letters that can be pronounced as /3:/?
A. e
B. ear
C. er
D. o
What are the letter or letters that can be pronounced as /ə/?
A. a
B. e
C. i
D. o
What’s the feature of pronouncing the central vowels?They are made with the tongue around the ___________ of the mouth. (答案要求为纯小写字母。)