The new staff didn’t know how to use the system _________ I explained it to him yesterday. ( )
·until
·because
·if
·since
出自:佳木斯大学语言治疗学

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