问题补充：
Between the two lectures a break, the audience can buy ice cream.
A. is; when
B. are; when
C. are; which
D. is; which
答案：
(答案→)A. is; when
B. are; when
C. are; which
D. is; which
解析：考查主谓一致和定语从句。前半句是倒装结构，正常语序应该是A break is between the two lectures，主语A break是单数，排除B、C，根据逗号判断是非限制性定语从句，先行词是a break，指的是时间，且定语从句the audience can buy ice cream主谓宾都有，不缺少成分，不用which引导，排除D，故选A。
