By the time he was 12, Edison ______ to make a living by himself. ( )(本题3.0分)
A、 would begin
B、 has begun
C、 had begun
D、 was begun
出自:井冈山大学英语2(专升本)

完成拼图验证

按住下方滑块,将拼图拖到缺口处后松开。

拼图背景,将小拼图拖到缺口处
向右拖动滑块