问题补充：
---Is that Jack speaking?
---Sorry, he in. He back in half an hour.
A. isn’t; will be
B. wasn’t; will
C. isn’t; is
D. wasn’t; was
答案：
(答案→)A. isn’t; will be
B. wasn’t; will
C. isn’t; is
D. wasn’t; was
解析：电话用语根据句意可知Jack不在家，半个小时后回来，不在家be not in＋一段时间表示多久之后，常用到将来时中
