20. John is busy ________ his girlfriend with her paper. A. to help B. helping C. help D. helps
出自:西北师范大学综合英语

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