问题
选择题
For our middle school students, some courses are compulsory, while others are ______. [ ]
A. flexible
B. optional
C. impressive
D. significant
答案
答案：B
搜题请搜索小程序“爱下问搜题”
For our middle school students, some courses are compulsory, while others are ______. [ ]
A. flexible
B. optional
C. impressive
D. significant
答案：B