why为什么选A呢?又为什么不选B 和D呢
27．—There aren't any toys in our suitcase．Where have you put them?
—Oh,no．That old lady sitting next to us ______ have taken ours by mistake.
A．must B．could C．should D．would
为什么选A呢?又为什么不选B 和D呢