It is essential that these application forms___back as early as possible.

A must be sent
B will be sent
C are sent

(D be sent
出自:吉林大学大学英语

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