she is going to tibet __vacation___December A for in B in in C for on D on on
问题描述：
she is going to tibet __vacation___December A for in B in in C for on D on on
答
b
答
选A
答
a，for表示去台北的原因，而december只是月份，所以加in，如果是确切的某一天则加on
答
When is she going to ...?
答
A
for vacation 度假 在某一月用in
答
for ,in
答
A for vacation
in December...
月份前只能用in，但vacation前不可能用in
答
A for in
答
选A。