问题
选择题
The mother was nervous because she had not her son who was away at a boarding school.
A．heard from
B．heard of
C．heard about
D．heard out
答案
答案：A
短语辨析。A收到sb的来信；B=C听说；D听完；根据句意可知A正确。句意：那位母亲很紧张，因为她很久没有收到在住宿学生学习的儿子的来信。