选择一个连词：I did not buy the watch yesterday( ) my mom would give me one.
问题描述：
选择一个连词：I did not buy the watch yesterday( ) my mom would give me one.
I did not buy the watch yesterday( ) my mom would give me one.
until?because?if?before?
我在想选第二个还是第三个呢
答
because
如果用if的话,前面的分句应该用现在时