问题
选择题
— Can you swim in the river?
— No, I _____. [ ]
A. mustn't
B. may not
C. can't
D. needn't
答案
答案：C
搜题请搜索小程序“爱下问搜题”
— Can you swim in the river?
— No, I _____. [ ]
A. mustn't
B. may not
C. can't
D. needn't
答案：C
力起缓冲作用的主要是（）